WorldWideScience

Sample records for surface transportation research

  1. 76 FR 50312 - Surface Transportation Environment and Planning Cooperative Research Program (STEP)

    Science.gov (United States)

    2011-08-12

    ... transportation safety planning strategies for surface transportation systems and improvements; (5) Improving... Federal Highway Administration Surface Transportation Environment and Planning Cooperative Research...-LU) established the Surface Transportation Environment and Planning Cooperative Research Program...

  2. 75 FR 38605 - Surface Transportation Environment and Planning Cooperative Research Program (STEP)

    Science.gov (United States)

    2010-07-02

    ... research to address congestion reduction efforts; (4) Developing transportation safety planning strategies... Federal Highway Administration Surface Transportation Environment and Planning Cooperative Research...-LU) established the Surface Transportation Environment and Planning Cooperative Research Program...

  3. Current status, research needs, and opportunities in applications of surface processing to transportation and utilities technologies. Proceedings of a December 1991 workshop

    Energy Technology Data Exchange (ETDEWEB)

    Czanderna, A.W.; Landgrebe, A.R. [eds.

    1992-09-01

    Goal of surface processing is to develop innovative methods of surface modification and characterization for optimum performance and environmental protection for cost-effective operational lifetimes of systems, materials, and components used in transportation and utilities. These proceedings document the principal discussions and conclusions reached at the workshop; they document chapters about the current status of surface characterization with focus on composition, structure, bonding, and atomic-scale topography of surfaces. Also documented are chapters on the current status of surface modification techniques: electrochemical, plasma-aided, reactive and nonreactive physical vapor deposition, sol-gel coatings, high-energy ion implantation, ion-assisted deposition, organized molecular assemblies, solar energy. Brief chapters in the appendices document basic research in surface science by NSF, Air Force, and DOE. Participants at the workshop were invited to serve on 10 working groups. Separate abstracts were prepared for the data base where appropriate.

  4. Transport research: Quo Vadis?

    CSIR Research Space (South Africa)

    Rust, FC

    2008-07-01

    Full Text Available It is well-recognised internationally that transport and transport infrastructure play a major role both in the stimulation of economic growth, creation of job opportunities and in poverty alleviation. This is of particular importance in South...

  5. Passenger transport research

    CSIR Research Space (South Africa)

    Mokonyama, Mathetha T

    2008-03-01

    Full Text Available In South Africa, airport and airline services epitomise what many would like to see in everyday public transport. The CSIR investigates what it will take to provide a commercial public transport service in South Africa which resembles commercial air...

  6. Transport Research Needs

    DEFF Research Database (Denmark)

    Ortúzar, Juan de Dios; Cherchi, Elisabetta; Rizzi, Luis

    2014-01-01

    of supply and demand in strategic planning contexts; the latter involving large zoning systems, huge multimodal networks and highly complex dynamic modelling approaches (Mahmassani, 2001). But questions also arise at a more macro level (and in a different time span) regarding the interaction of transport...... and land use, and also at the more micro level with the dynamics of road traffic and public transport modelling, an area which is particularly interesting due to its high complexity in less developed nations (de Cea et al., 2005). We do not have the expertise or the space to dwell on all these issues...

  7. Surface Traffic Management Research

    Science.gov (United States)

    Jung, Yoo Chul

    2012-01-01

    This presentation discusses an overview of the surface traffic management research conducted by NASA Ames. The concept and human-in-the-loop simulation of the Spot and Runway Departure Advisor (SARDA), an integrated decision support tool for the tower controllers and airline ramp operators, is also discussed.

  8. Surface transport in plasma-balls

    CERN Document Server

    Armas, Jay; Kundu, Nilay

    2015-01-01

    We study the surface transport properties of stationary localized configurations of relativistic fluids to the first two non-trivial orders in a derivative expansion. By demanding that these finite lumps of relativistic fluid are described by a thermal partition function with arbitrary stationary background metric and gauge fields, we are able to find several constraints among surface transport coefficients. At leading order, besides recovering the surface thermodynamics, we obtain a generalization of the Young-Laplace equation for relativistic fluid surfaces, by considering a temperature dependence in the surface tension, which is further generalized in the context of superfluids. At the next order, for uncharged fluids in 3+1 dimensions, we show that besides the 3 independent bulk transport coefficients previously known, a generic localized configuration is characterized by 3 additional surface transport coefficients, one of which may be identified with the surface modulus of rigidity. Finally, as an applic...

  9. Vacancy Transport and Interactions on Metal Surfaces

    Science.gov (United States)

    2014-03-06

    AFRL-OSR-VA-TR-2013-0317 VACANCY TRANSPORT AND INTERACTIONS ON METAL SURFACES Gert Ehrlich UNIVERSITY OF ILLINOIS CHAMPAIGN Final Report 03/06/2014...30, 2012 Gert Ehrlich , PI Abstract This proposal is a study of vacancy transport and vacancy interaction on metal surfaces. Adatom self...Trembułowicz, Gert Ehrlich , Grażyna Antczak,Surface diffusion of gold on quasihexagonal-reconstructed Au(100) ,Physical Review B 84 (2011) 245445-1

  10. Transportation Research Analysis Computing Center (TRACC)

    Data.gov (United States)

    Federal Laboratory Consortium — Argonne National Laboratory initiated a multi-year program with the US Department of Transportation (USDOT) in October 2006, to establish the Transportation Research...

  11. Surface transport in plasma-balls

    Energy Technology Data Exchange (ETDEWEB)

    Armas, Jay [Physique Théorique et Mathématique, Université Libre de Bruxelles andInternational Solvay Institutes,ULB-Campus Plaine CP231, B-1050 Brussels (Belgium); Bhattacharya, Jyotirmoy [Centre for Particle Theory & Department of Mathematical Sciences, Durham University,South Road, Durham DH1 3LE (United Kingdom); Kundu, Nilay [Harish-Chandra Research Institute,Chhatnag Road, Jhunsi, Allahabad 211019 (India)

    2016-06-06

    We study the surface transport properties of stationary localized configurations of relativistic fluids to the first two non-trivial orders in a derivative expansion. By demanding that these finite lumps of relativistic fluid are described by a thermal partition function with arbitrary stationary background metric and gauge fields, we are able to find several constraints among surface transport coefficients. At leading order, besides recovering the surface thermodynamics, we obtain a generalization of the Young-Laplace equation for relativistic fluid surfaces, by considering a temperature dependence in the surface tension, which is further generalized in the context of superfluids. At the next order, for uncharged fluids in 3+1 dimensions, we show that besides the 3 independent bulk transport coefficients previously known, a generic localized configuration is characterized by 3 additional surface transport coefficients, one of which may be identified with the surface modulus of rigidity. Finally, as an application, we study the effect of temperature dependence of surface tension on some explicit examples of localized fluid configurations, which are dual to certain non-trivial black hole solutions via the AdS/CFT correspondence.

  12. Surface transport in plasma-balls

    Science.gov (United States)

    Armas, Jay; Bhattacharya, Jyotirmoy; Kundu, Nilay

    2016-06-01

    We study the surface transport properties of stationary localized configurations of relativistic fluids to the first two non-trivial orders in a derivative expansion. By demanding that these finite lumps of relativistic fluid are described by a thermal partition function with arbitrary stationary background metric and gauge fields, we are able to find several constraints among surface transport coefficients. At leading order, besides recovering the surface thermodynamics, we obtain a generalization of the Young-Laplace equation for relativistic fluid surfaces, by considering a temperature dependence in the surface tension, which is further generalized in the context of superfluids. At the next order, for uncharged fluids in 3+1 dimensions, we show that besides the 3 independent bulk transport coefficients previously known, a generic localized configuration is characterized by 3 additional surface transport coefficients, one of which may be identified with the surface modulus of rigidity. Finally, as an application, we study the effect of temperature dependence of surface tension on some explicit examples of localized fluid configurations, which are dual to certain non-trivial black hole solutions via the AdS/CFT correspondence.

  13. Research on advanced transportation systems

    Science.gov (United States)

    Nagai, Hirokazu; Hashimoto, Ryouhei; Nosaka, Masataka; Koyari, Yukio; Yamada, Yoshio; Noda, Keiichirou; Shinohara, Suetsugu; Itou, Tetsuichi; Etou, Takao; Kaneko, Yutaka

    1992-08-01

    An overview of the researches on advanced space transportation systems is presented. Conceptual study is conducted on fly back boosters with expendable upper stage rocket systems assuming a launch capacity of 30 tons and returning to the launch site by the boosters, and prospect of their feasibility is obtained. Reviews are conducted on subjects as follows: (1) trial production of 10 tons sub scale engines for the purpose of acquiring hardware data and picking up technical problems for full scale 100 tons thrust engines using hydrocarbon fuels; (2) development techniques for advanced liquid propulsion systems from the aspects of development schedule, cost; (3) review of conventional technologies, and common use of component; (4) oxidant switching propulsion systems focusing on feasibility of Liquefied Air Cycle Engine (LACE) and Compressed Air Cycle Engine (CACE); (5) present status of slosh hydrogen manufacturing, storage, and handling; (6) construction of small high speed dynamometer for promoting research on mini pump development; (7) hybrid solid boosters under research all over the world as low-cost and clean propulsion systems; and (8) high performance solid propellant for upper stage and lower stage propulsion systems.

  14. Aspheric surface testing by irradiance transport equation

    Science.gov (United States)

    Shomali, Ramin; Darudi, Ahmad; Nasiri, Sadollah; Asgharsharghi Bonab, Armir

    2010-10-01

    In this paper a method for aspheric surface testing is presented. The method is based on solving the Irradiance Transport Equation (ITE).The accuracy of ITE normally depends on the amount of the pick to valley of the phase distribution. This subject is investigated by a simulation procedure.

  15. Magnetic Flux Transport at the Solar Surface

    CERN Document Server

    Jiang, J; Cameron, R H; Solanki, S K; Gizon, L; Upton, L

    2014-01-01

    After emerging to the solar surface, the Sun's magnetic field displays a complex and intricate evolution. The evolution of the surface field is important for several reasons. One is that the surface field, and its dynamics, sets the boundary condition for the coronal and heliospheric magnetic fields. Another is that the surface evolution gives us insight into the dynamo process. In particular, it plays an essential role in the Babcock-Leighton model of the solar dynamo. Describing this evolution is the aim of the surface flux transport model. The model starts from the emergence of magnetic bipoles. Thereafter, the model is based on the induction equation and the fact that after emergence the magnetic field is observed to evolve as if it were purely radial. The induction equation then describes how the surface flows -- differential rotation, meridional circulation, granular, supergranular flows, and active region inflows -- determine the evolution of the field (now taken to be purely radial). In this paper, we...

  16. INFLUENCE OF SEDIMENT TRANSPORT ON ARMORED SURFACES

    Institute of Scientific and Technical Information of China (English)

    Katinka KOLL; Andreas DITTRICH

    2001-01-01

    Laboratory experiments have been carried out to study the characteristics of sediment transport in steep streams. The question is discussed wether an armoured surfaces is destroyed due to the transport of material, because additional impulses are acting on it, or the layer is sheltered by the transported material, because a part of the stream power is used to move the material. According to the results of the presented experiments, in which the influence of the feeding rate and the feeding duration have been investigated, transported material reaching an armoured river section from upstream always remobilzes bed material, which is immobile under clear water flow conditions. To decide if a static armour layer is either destroyed or not, two simple criteria were chosen: oneconsidering the grain-size distribution of the eroded bed material, and another, which referes to the amount of eroded bed material.

  17. Turbulent transport in the atmospheric surface layer

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern [Dept. of Physical Geography and Ecosystem Science, Lund Univ., Lund (Sweden)

    2012-04-15

    In the modelling of transport and accumulation of the radioactive isotope carbon-14 (C-14) in the case of a potential release from a future repository of radioactive waste, it is important to describe the transport of the isotope in the atmosphere. This report aims to describe the turbulent transport within the lower part of the atmosphere; the inertial surface layer and the roughness sublayer. Transport in the inertial surface layer is dependent on several factors, whereof some can be neglected under certain circumstances. Under steady state conditions, fully developed turbulent conditions, in flat and horizontal homogeneous areas, it is possible to apply an eddy diffusivity approach for estimating vertical transport of C. The eddy diffusivity model assumes that there is proportionality between the vertical gradient and the transport of C. The eddy diffusivity is depending on the atmospheric turbulence, which is affected by the interaction between mean wind and friction of the ground surface and of the sensible heat flux in the atmosphere. In this report, it is described how eddy diffusivity of the inertial surface layer can be estimated from 3-d wind measurements and measurements of sensible heat fluxes. It is also described how to estimate the eddy diffusivity in the inertial surface layer from profile measurements of temperature and wind speed. Close to the canopy, wind and C profiles are influenced by effects of the surface roughness; this section of the atmosphere is called the roughness sublayer. Its height is up to {approx}3 times the height of the plant canopy. When the mean wind interacts with the canopy, turbulence is not only produced by shear stress and buoyancy, it is additionally created by wakes, which are formed behind the plants. Turbulence is higher than it would be over a flat surface, and the turbulent transport is hereby more efficient. Above the plant canopy, but still within the roughness sublayer, a function that compensates for the effect

  18. Turbulent transport in the atmospheric surface layer

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern [Dept. of Physical Geography and Ecosystem Science, Lund Univ., Lund (Sweden)

    2012-04-15

    In the modelling of transport and accumulation of the radioactive isotope carbon-14 (C-14) in the case of a potential release from a future repository of radioactive waste, it is important to describe the transport of the isotope in the atmosphere. This report aims to describe the turbulent transport within the lower part of the atmosphere; the inertial surface layer and the roughness sublayer. Transport in the inertial surface layer is dependent on several factors, whereof some can be neglected under certain circumstances. Under steady state conditions, fully developed turbulent conditions, in flat and horizontal homogeneous areas, it is possible to apply an eddy diffusivity approach for estimating vertical transport of C. The eddy diffusivity model assumes that there is proportionality between the vertical gradient and the transport of C. The eddy diffusivity is depending on the atmospheric turbulence, which is affected by the interaction between mean wind and friction of the ground surface and of the sensible heat flux in the atmosphere. In this report, it is described how eddy diffusivity of the inertial surface layer can be estimated from 3-d wind measurements and measurements of sensible heat fluxes. It is also described how to estimate the eddy diffusivity in the inertial surface layer from profile measurements of temperature and wind speed. Close to the canopy, wind and C profiles are influenced by effects of the surface roughness; this section of the atmosphere is called the roughness sublayer. Its height is up to {approx}3 times the height of the plant canopy. When the mean wind interacts with the canopy, turbulence is not only produced by shear stress and buoyancy, it is additionally created by wakes, which are formed behind the plants. Turbulence is higher than it would be over a flat surface, and the turbulent transport is hereby more efficient. Above the plant canopy, but still within the roughness sublayer, a function that compensates for the effect

  19. Transportation Institute dedicates new research building

    OpenAIRE

    Box, Sherri

    2006-01-01

    Today, with The Honorable John Warner as the keynote speaker, the Virginia Tech Transportation Institute (VTTI) dedicated its new 22,000 square-foot building in Blacksburg as the National Surface Transportation Safety Center for Excellence (STSCE). University administrators as well as other local and state officials also attended.

  20. 29 CFR 1926.902 - Surface transportation of explosives.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Surface transportation of explosives. 1926.902 Section 1926... Explosives § 1926.902 Surface transportation of explosives. (a) Transportation of explosives shall meet the... Carriers. (b) Motor vehicles or conveyances transporting explosives shall only be driven by, and be in the...

  1. 气道表面液转运与囊性纤维化肺病的病因研究%Airway surface liquid transport and pathogenesis research of cystic fibrosis lung disease

    Institute of Scientific and Technical Information of China (English)

    臧传宝; 卢丽丽; 王晓飞

    2009-01-01

    It has been considered that dysfunction of ions and liquid transport in airway epithelia is a main pathogenic factor of genetic cystic fibrosis lung disease. However, the problem about how airway surface liquid transport makes cystic fibrosis lung inflamed and impaired, has been argued in researches. Starting with explaining the cellular mechanisms of airway surface liquid transport, this article reviews the pathologic and genetic characteristics of cystic fibrosis lung disease and the research progress of late years in cystic fibrosis pathogenesis.%呼吸道上皮的离子和液体的转运功能失调,一直被认为是遗传性疾病囊性纤维化肺病的主要致病因素,但学术界对气道表面液转运缺陷如何引致囊性纤维化肺的感染和受损存在不同的观点.本文从解释气道表面液转运的细胞机制入手,综述了囊性纤维化肺病的病理和遗传特征和近年国际上对囊性纤维化肺病病因的研究进展.

  2. Transportation Research & Analysis Computing Center

    Data.gov (United States)

    Federal Laboratory Consortium — The technical objectives of the TRACC project included the establishment of a high performance computing center for use by USDOT research teams, including those from...

  3. Transportation Research & Analysis Computing Center

    Data.gov (United States)

    Federal Laboratory Consortium — The technical objectives of the TRACC project included the establishment of a high performance computing center for use by USDOT research teams, including those from...

  4. Public transportation 1995: Current research in operations. Transportation research record

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    ;Contents: Metromover Extensions and Downtown Bus Service in Miami; Electric Bus Operation and Evaluation in California; Assessment of Alternative Structures for Privately Operated Bus Systems; Bus Priority at Traffic Signals in Portland: The Powell Boulevard Pilot Project; Transit Vehicle-Type Scheduling Problem; Optimal Mixed Bus Fleet for Urban Operations; Operational Characteristics of Paratransit in Developing Countries of Asia; Economics of Electric Trolley Coach Operation; Evaluation of Visual Impacts of Trolleybus Overhead Caternary System Intersections; Electric and Magnetic Fields and Electric Transit Systems; Diverting Automobile Users to Transit: Early Lessons from the Chicago Transit Authority`s Orange Line; Street-Running Rail Transit: A Historical Perspective; Diesel or Electric Power for Commuter Rail; It Depends; Generic Objectives for Evaluation of Intermodal Passenger Transfer Facilities; Airport Ground Access: Rail Transit Alternatives; Retrofit Techniques for Floating Slab Track; Calgary Light Rail Transit Surface Operations and Grade-Level Crossings; and Cost of Light Rail Collision Accidents.

  5. Characterizing Surface Transport Barriers in the South China Sea

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Characterizing Surface Transport Barriers in the South...in mathematical methods for detecting key Lagrangian transport structures in velocity field data sets for spatially complex, time- dependent, ocean...surface flows. Such transport structures are typically not inherently obvious in snapshots of the Eulerian velocity field and require analysis

  6. Lagrangian Transport Through Surfaces in Volume-Preserving Flows

    CERN Document Server

    Karrasch, Daniel

    2015-01-01

    Advective transport of scalar quantities through surfaces is of fundamental importance in many scientific applications. From the Eulerian perspective of the surface it can be quantified by the well-known integral of the flux density. The recent development of highly accurate semi-Lagrangian methods for solving scalar conservation laws and of Lagrangian approaches to coherent structures in turbulent (geophysical) fluid flows necessitate a new approach to transport from the (Lagrangian) material perspective. We present a Lagrangian framework for calculating transport of conserved quantities through a given surface in $n$-dimensional, fully aperiodic, volume-preserving flows. Our approach does not involve any dynamical assumptions on the surface or its boundary.

  7. Modeling sheet-flow sand transport under progressive surface waves

    NARCIS (Netherlands)

    Kranenburg, W.M.

    2013-01-01

    In the near-shore zone, energetic sea waves generate sheet-flow sand transport. In present day coastal models, wave-induced sheet-flow sand transport rates are usually predicted with semi-empirical transport formulas, based on extensive research on this phenomenon in oscillatory flow tunnels. Howeve

  8. Nonlinear Transport In Gases, Traps And Surfaces

    Science.gov (United States)

    Šuvakov, M.; Marjanovic, S.

    2010-07-01

    We will present our numerical study of three different charge transport processes and we will compare properties, specially the nonlinearity, of these processes. First process is electron transport in gases in swarm regime. We used well tested Monte Carlo techique to investigate kinetic phenomena such as negative diferencial conductivity (NDC) or negative apsolute mobility (NAM). We explain these phenomena analysing the spatial profiles of the swarm and collision events. In the second part we will apply the same technique on positron transport to obtain the same level of understanding of positron transport as has been achieved for electrons. The influence of positronium formation, non-conservative process, is much larger than any comparable effects in electron transport due to attachment and/or ionisation. As a result several new phenomena have been observed, such as NDC for the bulk drift velocity. Additionaly, the same Monte Carlo technique is used for modeling and optimisation of Surko like positron traps in different geometries and field configurations. Third process we studied is the charge transport under voltage bias via single-electron tunnelings through the junctions between metallic particles on nanoparticle films. We show how the regular nanoparticle array and topologically inhomogeneous nanonetworks affect the charge transport. We find long-range correlations in the time series of charge fluctuation at individual nanoparticles and of flow along the junctions within the network. These correlations explain the occurrence of a large non-linearity in the simulated and experimentally measured current-voltage characteristics and non-Gaussian fluctuations of the current at the electrode.

  9. Oil droplet self-transportation on oleophobic surfaces

    Science.gov (United States)

    Li, Juan; Qin, Qi Hang; Shah, Ali; Ras, Robin H. A.; Tian, Xuelin; Jokinen, Ville

    2016-01-01

    Directional liquid transportation is important for a variety of biological processes and technical applications. Although surface engineering through asymmetric chemical modification or geometrical patterning facilitates effective liquid manipulation and enables water droplet self-transportation on synthetic surfaces, self-transportation of oil droplets poses a major challenge because of their low surface tension. We report oil droplet self-transportation on oleophobic surfaces that are microtextured with radial arrays of undercut stripes. More significantly, we observe three modes of oil motion on various sample surfaces, namely, inward transportation, pinned, and outward spreading, which can be switched by the structure parameters, including stripe intersection angle and width. Accompanying theoretical modeling provides an in-depth mechanistic understanding of the structure–droplet motion relationship. Finally, we reveal how to optimize the texture parameters to maximize oil droplet self-transportation capability and demonstrate spontaneous droplet movement for liquids down to a surface tension of 22.4 mN/m. The surfaces presented here open up new avenues for power-free liquid transportation and oil contamination self-removal applications in various analytical and fluidic devices. PMID:27386574

  10. Comparison of alternative concepts for lunar surface transportation

    Science.gov (United States)

    Apel, Uwe

    The lunar surface transportation system is a key element in lunar development. The decision which means of conveyance should be preferred depends on a lot of influencing factors such as transportation requirements, physical boundary conditions and economics. Starting with a systematic approach to define and structure the problem, a model to compare alternative transportation systems has been built. From the pool of possible means of conveyance, chemical rockets, electric cars, maglev-trains and mass-drivers have been chosen as candidates for investigation. With these candidates five different surface transportation systems were defined. For a reference lunar development scenario the systems were compared on the basis of a cost-to-benefit ratio. Preliminary results indicate that under the assumption that LH2 could be produced on lunar surface, LOX/LH2 propulsed "Hoppers" seem very attractive up to medium transportation demands. For large amounts of bulk cargo, mass driver transportation seems to have advantages, and electric cars should be used for all transportation tasks if the transportation demand is high. Maglev-trains seem to be competitive only for very large transportation demand and long life cycles.

  11. Vertical Transport of Subwavelength Localized Surface Electromagnetic Modes

    CERN Document Server

    Gao, Fei; Zhang, Youming; Shi, Xihang; Yang, Zhaoju; Zhang, Baile

    2015-01-01

    Transport of subwavelength electromagnetic (EM) energy has been achieved through near-field coupling of highly confined surface EM modes supported by plasmonic nanoparticles, in a configuration usually staying on a two-dimensional (2D) substrate. Vertical transport of similar modes along the third dimension, on the other hand, can bring more flexibility in designs of functional photonic devices, but this phenomenon has not been observed in reality. In this paper, designer (or spoof) surface plasmon resonators (plasmonic meta-atoms) are stacked in the direction vertical to their individual planes in demonstrating vertical transport of subwavelength localized surface EM modes. Dispersion relation of this vertical transport is determined from coupled mode theory and is verified with near-field transmission spectrum and field mapping with a microwave near-field scanning stage. This work extends the near-field coupled resonator optical waveguide (CROW) theory into the vertical direction, and may find applications ...

  12. Aeolian transport in the field: A comparison of the effects of different surface treatments

    Science.gov (United States)

    Dong, Zhibao; Lv, Ping; Zhang, Zhengcai; Qian, Guangqiang; Luo, Wanyin

    2012-05-01

    Aeolian transport represents the result of wind-surface interactions, and therefore depends strongly on variations in the characteristics of the sediment surface. We conducted field observations of aeolian transport of typical dune sand in three 80 m × 80 m plots with different surface treatments: gravel-covered sand, enclosed shifting sand, and open (unprotected) shifting sand. The study was performed at the Shapotou Aeolian Experiment Site in the southeastern part of China's Tengger Desert to compare the effects of these different surface treatments on aeolian transport. To do so, we analyzed the flux density profiles and transport rates above each surface. The flux density profiles for all three treatments followed the exponential decay law that was proposed by most previous researchers to describe the saltation flux density profiles. Coefficients of the exponential decay function were defined as a function of the surface and the wind velocity. The enclosed and open plots with shifting sand had similar flux density profiles, but the flux density above gravel-covered plots showed that transport decayed more slowly with increasing height, producing flux density profiles with a higher average saltation height. The transport rate above the three treatment plots tended to increase proportionally with the cube of the mean wind velocity and with the maximum wind velocity during the observation period, but was more strongly correlated with the square of drift potential. Transport rates above the plot with open shifting sand were greater than those above the plots with enclosed shifting sand and the gravel-covered plot.

  13. Models of Fate and Transport of Pollutants in Surface Waters

    Science.gov (United States)

    Okome, Gloria Eloho

    2013-01-01

    There is the need to answer very crucial questions of "what happens to pollutants in surface waters?" This question must be answered to determine the factors controlling fate and transport of chemicals and their evolutionary state in surface waters. Monitoring and experimental methods are used in establishing the environmental states.…

  14. Models of Fate and Transport of Pollutants in Surface Waters

    Science.gov (United States)

    Okome, Gloria Eloho

    2013-01-01

    There is the need to answer very crucial questions of "what happens to pollutants in surface waters?" This question must be answered to determine the factors controlling fate and transport of chemicals and their evolutionary state in surface waters. Monitoring and experimental methods are used in establishing the environmental states.…

  15. Development of the public transport research compendium portal

    CSIR Research Space (South Africa)

    Dimitrov, L

    2009-07-01

    Full Text Available passenger transport research agenda in South Africa. Cameron (2005) recommends research to be undertaken to assess the potential of new technology for efficient data collection based on scientific reasoning. In Conclusion, Mokonyama and Schnakenberg... African Transport Conference (SATC), Pretoria. Cameron, J.W.M. (2005), Questions about the quantitative basis of municipal transport plans, Proceedings of the 24th Southern African Transport Conference (SATC), Pretoria, pp. 680-695 CSIR Research Space...

  16. Studying Polymer Transport on Soft and Hard Surfaces

    Science.gov (United States)

    Kumar, Sanat

    2007-03-01

    We have employed experiments and simulations to understand the factors controlling the transport of polymers on surfaces. From an experimental viewpoint we have focused on the transport of DNA (single stranded) on lipid bilayers. We show that this behavior is slaved to the mobility of the lipids. More surprisingly, it appears that the transport of molecules adsorbed on surfaces follows the same dependence on lipid mobility as for molecules incorporated into the lipid layer. The ability to control this surface diffusion through the introduction of posts or varying the strength of adsorption (by the use of an AC field normal to the surfaces) will also be studied. Theoretically we have used molecular dynamics simulations of a polymer chain of length N dissolved in explicit solvent and adsorbed as a pancake at the solid-liquid interface to discriminate between respective influences on surface diffusion of hydrodynamics and adsorption energetics. Only for analytically-smooth surfaces do we observe a strong influence of hydrodynamics; the polymer lateral diffusion constant, D, scales as D 1/N^3/4, more weakly than for implicit solvent. For atomistic surface corrugation with uniform surface chemical makeup, D 1/N instead. This suggests that while we can understand the results for diffusion on lipid surfaces, more recent experimental observations of stronger N dependence for diffusion on hard solid surfaces originate not in hydrodynamic interactions but in spatially patchy energetic interactions.

  17. Sea surface temperature and Ekman transport in the Persian Gulf

    Directory of Open Access Journals (Sweden)

    E. H.

    2002-12-01

    Full Text Available   The wind drift motion of the water which is produced by the stress of the wind exerted upon the surface of the ocean is described by Ekmans theory (1905. Using the mean monthly values for the wind stress and SST, seasonal Ekman transport for the Persian Gulf was computed and contoured. The geostrophic winds have combined with the SST to estimate the effect of cooling due to Ekman transport of colder northern waters and inflow from the Oman Sea. The monthly SST mainly obtained from the 10 10 grided data of Levitus atlas and Hormuz Cruis Experiment for 1997.   Analyses show a NW to SE Ekman transport due to wind stress and significant interannual variability of SST on sea surface in the Persian Gulf. The seasonal variation of SST shows a continental pattern due to severe interaction between the land and sea. But these variations somehow moderates because of Ekman transport in Persian Gulf.

  18. Research on the application of VRP theory in logistics transportation

    Directory of Open Access Journals (Sweden)

    Zhu Ruiqi

    2017-01-01

    Full Text Available Logistics transportation problem is a hot issue in today’s research, with the diversification of transport vehicles, the complexity of the transportation network, the choice of logistics transportation route is a NP problem in combinatorial optimization. The paper discusses the relevant knowledge of VRP and physical distribution routing, such as the relationship between them, how to describe the distribution problem with VRP, how to build up mathematical model and so on and meanwhile, points out the direction of research.

  19. Water transport mechanism through open capillaries analyzed by direct surface modifications on biological surfaces

    Science.gov (United States)

    Ishii, Daisuke; Horiguchi, Hiroko; Hirai, Yuji; Yabu, Hiroshi; Matsuo, Yasutaka; Ijiro, Kuniharu; Tsujii, Kaoru; Shimozawa, Tateo; Hariyama, Takahiko; Shimomura, Masatsugu

    2013-10-01

    Some small animals only use water transport mechanisms passively driven by surface energies. However, little is known about passive water transport mechanisms because it is difficult to measure the wettability of microstructures in small areas and determine the chemistry of biological surfaces. Herein, we developed to directly analyse the structural effects of wettability of chemically modified biological surfaces by using a nanoliter volume water droplet and a hi-speed video system. The wharf roach Ligia exotica transports water only by using open capillaries in its legs containing hair- and paddle-like microstructures. The structural effects of legs chemically modified with a self-assembled monolayer were analysed, so that the wharf roach has a smart water transport system passively driven by differences of wettability between the microstructures. We anticipate that this passive water transport mechanism may inspire novel biomimetic fluid manipulations with or without a gravitational field.

  20. Surface hall effect and nonlocal transport in SmB₆: evidence for surface conduction.

    Science.gov (United States)

    Kim, D J; Thomas, S; Grant, T; Botimer, J; Fisk, Z; Xia, Jing

    2013-11-06

    A topological insulator (TI) is an unusual quantum state in which the insulating bulk is topologically distinct from vacuum, resulting in a unique metallic surface that is robust against time-reversal invariant perturbations. The surface transport, however, remains difficult to isolate from the bulk conduction in most existing TI crystals (particularly Bi₂Se₃, Bi₂Te₃ and Sb₂Te₃) due to impurity caused bulk conduction. We report in large crystals of topological Kondo insulator (TKI) candidate material SmB₆ the thickness-independent surface Hall effects and non-local transport, which persist after various surface perturbations. These results serve as proof that at low temperatures SmB₆ has a metallic surface that surrounds an insulating bulk, paving the way for transport studies of the surface state in this proposed TKI material.

  1. TRANSPORTATION RESEARCH CONTRIBUTIONS TO SOCIETY BY UNIVERSITY TRANSPORTATION CENTERS

    Directory of Open Access Journals (Sweden)

    Robert C. JOHNS

    2003-01-01

    Full Text Available This paper discusses the importance of knowledge in the global economy and reviews the process in which knowledge is applied to develop innovations. It confirms the importance of innovation as a key factor for success in today's competitive environment. The paper discusses the contributions a university can make to the innovation process in the field of transportation, and offers a vision of how a university center can enhance and facilitate these contributions. It then describes the efforts of one center, including three examples of innovations facilitated by the center in traffic detection, regional planning, and pavement management. The paper concludes with suggestions that would strengthen the societal contributions of university transportation centers.

  2. Directional transport of impinging capillary jet on wettability engineered surfaces

    Science.gov (United States)

    Ghosh, Aritra; Chatterjee, Souvick; Sinha Mahapatra, Pallab; Ganguly, Ranjan; Megaridis, Constantine

    2015-11-01

    Impingement of capillary jet on a surface is important for applications like heat transfer, or for liquid manipulation in bio-microfluidic devices. Using wettability engineered surfaces, we demonstrate pump-less and directional transport of capillary jet on a flat surface. Spatial contrast of surface energy and a wedge-shape geometry of the wettability confined track on the substrate facilitate formation of instantaneous spherical bulges upon jet impingement; these bulges are further transported along the superhydrophilic tracks due to Laplace pressure gradient. Critical condition warranted for formation of liquid bulge along the varying width of the superhydrophilic track is calculated analytically and verified experimentally. The work throws light on novel fluid phenomena of unidirectional jet impingement on wettability confined surfaces and provides a platform for innovative liquid manipulation technique for further application. By varying the geometry and wettability contrast on the surface, one can achieve volume flow rates of ~ O(100 μL/sec) and directionally guided transport of the jet liquid, pumplessly at speeds of ~ O(10cm/sec).

  3. Modeling marine surface microplastic transport to assess optimal removal locations

    NARCIS (Netherlands)

    Sherman, Peter; Van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics f

  4. Modeling marine surface microplastic transport to assess optimal removal locations

    NARCIS (Netherlands)

    Sherman, Peter; Van Sebille, Erik|info:eu-repo/dai/nl/304831921

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics

  5. Barents Sea heat – transport, storage and surface fluxes

    Directory of Open Access Journals (Sweden)

    Ø. Skagseth

    2009-07-01

    Full Text Available Sensitivity of the Barents Sea to variation in ocean heat transport and surface fluxes is explored using a 1-D column model. Mean monthly ocean transport and atmospheric forcing are synthesised and force model results that reproduce the observed winter convection and surface warming and freshening well. Model results are compared to existing estimates of the ocean to air heat fluxes and horizontally averaged profiles for the southern and northern Barents Sea. Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production. The northern Barents Sea, the major part of the area, receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss in the north, the balance is achieved by long wave loss removing most of the solar heating, and the model also suggests a positive sensible heat gain. During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. Despite large changes the Barents Sea heat loss remains robust, the temperature adjusts, and the yearly cycle remains. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport probably leads to a spreading of warm water further north.

  6. STM tip-mediated mass transport on Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.S.N. [College of Physical Science and Technology, Shenyang Normal University, Huanghe Street 253, Shenyang 110034 (China); Huang, R.Z., E-mail: renzhonghuang@synu.edu.cn [College of Physical Science and Technology, Shenyang Normal University, Huanghe Street 253, Shenyang 110034 (China); Gao, T.F. [College of Physical Science and Technology, Shenyang Normal University, Huanghe Street 253, Shenyang 110034 (China); Zhang, R.J. [School of Information Science and Engineering, Fudan University, Handan Road 220, Shanghai 200433 (China); Wang, Y.M. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016 (China)

    2015-02-01

    Highlights: • Tip-induced atomic motion of Co atoms embedded in the Cu (0 0 1) surface in the presence of vacancies. • Interlayer mass transport at the island edge is found to depend strongly on the tip height and the lateral distance from the tip. • The jumping and the Ehrlich–Schwoebel (E–S) diffusion barrier can be reduced by tip manipulation. - Abstract: Atomic-scale simulations are performed to study atomic motion on Cu surfaces to illustrate the effect of the scanning tunneling microscopy tip on mass transport (MT) in the surfaces and on top of the Co island in heteroepitaxial Co/Cu(0 0 1) and Co/Cu(1 1 1) systems. First we investigate tip-induced atomic motion of Co atoms embedded in the Cu(0 0 1) surface at zero bias voltage. With the help of the tip, the Co atom in the surface can freely diffuse toward its nearby vacancy site. So-called vacancy mechanism is used to interpret this phenomenon. Then tip-mediated atomic motion of Co adatoms on the Co islands supported by a Cu(1 1 1) surface is studied. It is revealed that the tip has a significant effect on the diffusion of adatoms on the islands and interlayer mass transport at the island edge. Interlayer mass transport at the island edge is found to depend strongly on the tip height and the lateral distance from the tip. By calculating the diffusion barriers, it is found that the jumping diffusion barrier on the island can be zero by the tip vertical manipulation while the Ehrlich–Schwoebel diffusion barrier at the island edge can be reduced by the tip lateral manipulation. Thus, the quality of thin films can be improved by controlling MT in and/or on the surface.

  7. Heat in the Barents Sea: transport, storage, and surface fluxes

    Directory of Open Access Journals (Sweden)

    L. H. Smedsrud

    2010-02-01

    Full Text Available A column model is set up for the Barents Sea to explore sensitivity of surface fluxes and heat storage from varying ocean heat transport. Mean monthly ocean transport and atmospheric forcing are synthesised and force the simulations. Results show that by using updated ocean transports of heat and freshwater the vertical mean hydrographic seasonal cycle can be reproduced fairly well.

    Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production.

    The northern Barents Sea receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss annually in the north. The balance is achieved by a heat loss through long wave radiation all year, removing most of the summer solar heating.

    During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. The Barents Sea responds to such large changes by adjusting temperature and heat loss. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport leads to a spreading of warm water further north.

  8. Excess Surface Area in Bioelectrochemical Systems Causes ion Transport Limitations

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Timothy D.; Babauta, Jerome T.; Davenport, Emily K.; Renslow, Ryan S.; Beyenal, Haluk

    2015-05-01

    We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200mM increased current linearly up to a total of þ273% vs. 0mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un-colonized surface area remained even after steadystate current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non-zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant.

  9. Quantum Transport and Surface Scattering in Magnetic Metallic Film

    Institute of Scientific and Technical Information of China (English)

    HU Yin; DONG Zheng-Chao

    2008-01-01

    Taking into account the quantum size effect and the spin dependence of the electronic band structure,and including the spin dependence of the scattering from bulk impurities and two different sets of surface roughness,we present a theory on the electronic transport in magnetic film,in which the average autocorrelation function (ACF) for surface roughness is described by a Gaussion model.Our result shows that the conductivity is a sensitive function of surface roughness and exchange energy.It is also found that in the thin film limit and in the lower-order approximation of the surface scattering,the total conductivity is given by a sum of conductivities of all the subbands and the two spin channels,for each subband and each spin channel the scattering rates due to the impurities and two surfaces are additive.

  10. Research and application of nanotechnology in transportation

    CSIR Research Space (South Africa)

    Steyn, WJvdM

    2008-07-01

    Full Text Available effects that the technology may have on aspects such as safety, durability, economics and sustainability of the transportation infrastructure. The most important challenge in this endeavour is that of scaling nanotechnology to ensure that the benefits...

  11. Band bending and electrical transport at chemically modified silicon surfaces

    Science.gov (United States)

    Lopinski, Greg; Ward, Tim; Hul'Ko, Oleksa; Boukherroub, Rabah

    2002-03-01

    High resolution electron energy loss spectroscopy (HREELS) and electrical transport measurements have been used to investigate how various chemical modifications give rise to band bending and alter the conductivity of Si(111) surfaces. HREELS is a sensitive probe of band bending through observations of the low frequency free carrier plasmon mode. For hydrogen terminated surfaces, prepared by the standard etch in ammonium flouride, HREELS measurements on both n and n+ substrates are consistent with nearly flat bands. Chlorination of these surfaces results in substantial upward band bending due to the strong electron withdrawing nature of the chlorine, driving the surface into inversion. The presence of this inversion layer on high resistivity n-type samples is observed through a substantial enhancement of the surface conductivity (relative to the H-terminated surface), as well as through broadening of the quasi-elastic peak in the HREELS measurements. We have also begun to examine organically modified silicon surfaces, prepared by various wet chemical reactions with the H-terminated surface. Decyl modified Si(111) surfaces are seen to exhibit a small degree of band bending, attributed to extrinsic defect states cause by a small degree of oxidation accompanying the modification reaction. The prospects of using conductivity as an in-situ monitor of the rate of these reactions will be discussed.

  12. Droplet Transport Mechanism on Horizontal Hydrophilic/Hydrophobic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook [Kookmin University, Seoul (Korea, Republic of)

    2014-06-15

    A fluid transport technique is a key issue for the development of microfluidic systems. In this study, the movement of a droplet on horizontal hydrophilic/hydrophobic surfaces, which is a new concept to transport droplets without external power sources that was recently proposed by the author, was simulated using an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The droplet transport mechanism is examined through numerical results that include velocity vectors, pressure contours, and total kinetic energy inside and around the droplet.

  13. Surface Diffusion Effect on Gas Transport in Nanoporous Materials

    Science.gov (United States)

    Hori, Takuma; Yoshimoto, Yuta; Takagi, Shu; Kinefuchi, Ikuya

    2016-11-01

    Polymer electrolyte fuel cells are one of the promising candidates for power sources of electric vehicles. For further improvement of their efficiency in high current density operation, a better understanding of oxygen flow inside the cells, which have micro- or nanoporous structures, is necessary. Molecular simulations such as the direct simulation of Monte Carlo (DSMC) are necessary to elucidate flow phenomena in micro- or nanostructures since the Knudsen number is close to unity. Our previous report showed that the oxygen diffusion resistance in porous structures with a characteristic pore size of 100 nm calculated by DSMC agrees well with that measured experimentally. On the other hand, when it comes to the transport in structures with much smaller pore sizes, it is expected that the surface diffusion has a significant impact on gas transport because of their higher specific surface area. Here we present the calculation of gas transport in porous structures with considering surface diffusion. The numerical porous structure models utilized in our simulations are constructed from three-dimensional imaging of materials. The effect of the distance of random walk on the total diffusion resistance in the structures is discussed. This paper is based on results obtained from a project commissioned by the New Energy and Industrial Development Organization (NEDO).

  14. Applications of asymmetric nanotextured parylene surface using its wetting and transport properties

    Science.gov (United States)

    Sekeroglu, Koray

    In this thesis, basic digital fluidics devices were introduced using polymeric nanorods (nano-PPX) inspired from nature. Natural inspiration ignited this research by observing butterfly wings, water strider legs, rye grass leaves, and their asymmetric functions. Nano-PPX rods, manufactured by an oblique angle polymerization (OAP) method, are asymmetrically aligned structures that have unidirectional wetting properties. Nano-PPX demonstrates similar functions to the directional textured surfaces of animals and plants in terms of wetting, adhesion, and transport. The water pin-release mechanism on the asymmetric nano-PPX surface with adhesion function provides a great transport property. How the asymmetry causes transport is discussed in terms of hysteresis and interface contact of water droplets. In this study, the transport property of nano-PPX rods is used to guide droplets as well as transporting cargo such as microgels. With the addition of tracks on the nano-PPX rods, the surfaces were transformed into basic digital fluidics devices. The track-assisted nano-PPX has been employed to applications (i.e. sorting, mixing, and carrying cargo particles). Thus, digital fluidics devices fabricated on nano-PPX surface is a promising pathway to assemble microgels in the field of bioengineering. The characterization of the nano textured surface was completed using methods such as Scanning Electron Microscopy, Atomic Force Microscopy, Contact Angle Goniometry, and Fourier Transform Infra-Red Spectroscopy. These methods helped to understand the physical and chemical properties of nano-PPX. Parameters such as advancing and receding contact angles, nanorod tilt angle, and critical drop volumes were utilized to investigate the anisotropic wetting properties of nano-PPX surface. This investigation explained the directional wetting behavior of the surface as well as approaching new design parameters for adjusting surface properties. The nanorod tilt angle was a key parameter

  15. Slippery Liquid-Infused Porous Surfaces and Droplet Transportation by Surface Acoustic Waves

    Science.gov (United States)

    Luo, J. T.; Geraldi, N. R.; Guan, J. H.; McHale, G.; Wells, G. G.; Fu, Y. Q.

    2017-01-01

    On a solid surface, a droplet of liquid will stick due to the capillary adhesion, and this causes low droplet mobility. To reduce contact line pinning, surface chemistry can be coupled to micro- and/or nanostructures to create superhydrophobic surfaces on which a droplet balls up into an almost spherical shape, thus, minimizing the contact area. Recent progress in soft matter has now led to alternative lubricant-impregnated surfaces capable of almost zero contact line pinning and high droplet mobility without causing droplets to ball up and minimize the contact area. Here we report an approach to surface-acoustic-wave- (SAW) actuated droplet transportation enabled using such a surface. These surfaces maintain the contact area required for efficient energy and momentum transfer of the wave energy into the droplet while achieving high droplet mobility and a large footprint, therefore, reducing the threshold power required to induce droplet motion. In our approach, we use a slippery layer of lubricating oil infused into a self-assembled porous hydrophobic layer, which is significantly thinner than the SAW wavelength, and avoid damping of the wave. We find a significant reduction (up to 85%) in the threshold power for droplet transportation compared to that using a conventional surface-treatment method. Moreover, unlike droplets on superhydrophobic surfaces, where interaction with the SAW induces a transition from a Cassie-Baxter state to a Wenzel state, the droplets on our liquid-impregnated surfaces remain in a mobile state after interaction with the SAW.

  16. Spatiotemporal Structure of Aeolian Particle Transport on Flat Surface

    Science.gov (United States)

    Niiya, Hirofumi; Nishimura, Kouichi

    2017-05-01

    We conduct numerical simulations based on a model of blowing snow to reveal the long-term properties and equilibrium state of aeolian particle transport from 10-5 to 10 m above the flat surface. The numerical results are as follows. (i) Time-series data of particle transport are divided into development, relaxation, and equilibrium phases, which are formed by rapid wind response below 10 cm and gradual wind response above 10 cm. (ii) The particle transport rate at equilibrium is expressed as a power function of friction velocity, and the index of 2.35 implies that most particles are transported by saltation. (iii) The friction velocity below 100 µm remains roughly constant and lower than the fluid threshold at equilibrium. (iv) The mean particle speed above 300 µm is less than the wind speed, whereas that below 300 µm exceeds the wind speed because of descending particles. (v) The particle diameter increases with height in the saltation layer, and the relationship is expressed as a power function. Through comparisons with the previously reported random-flight model, we find a crucial problem that empirical splash functions cannot reproduce particle dynamics at a relatively high wind speed.

  17. Spatiotemporal Structure of Aeolian Particle Transport on Flat Surface

    CERN Document Server

    Niiya, Hirofumi

    2016-01-01

    We conduct numerical simulations based on a model of blowing snow to reveal the long-term properties and equilibrium state of aeolian particle transport from $10^{-5} \\hspace{0.5 ex} \\mathrm{m}$ to $10 \\hspace{0.5 ex} \\mathrm{m}$ above the flat surface. The numerical results are s follows. (i) Time-series data of particle transport are divided into development, relaxation, and equilibrium phases, which are formed by rapid wind response below $10 \\hspace{0.5 ex} \\mathrm{cm}$ and gradual wind response above $10 \\hspace{0.5 ex} \\mathrm{cm}$. (ii) The particle transport rate at equilibrium is expressed as a power function of friction velocity, and the index of 2.35 implies that most particles are transported by saltation. (iii) The friction velocity below $100 \\hspace{0.5 ex} \\mu\\mathrm{m}$ remains roughly constant and lower than the fluid threshold at equilibrium. (iv) The mean particle speed above $300 \\hspace{0.5 ex} \\mu\\mathrm{m}$ is less than the wind speed, whereas that below $300 \\hspace{0.5 ex} \\mu\\mathrm...

  18. Methods, measures and indicators for evaluating benefits of transportation research

    CSIR Research Space (South Africa)

    Du Plessis, Louw

    2016-04-01

    Full Text Available The purpose of this article is to provide updated information by identifying and discussing methods, measures and indicators for evaluating benefits appropriate for transportation-related research facilities/programmes. The information has been...

  19. research efforts on intelligent transportation system in nigeria

    African Journals Online (AJOL)

    user

    Keywords: Intelligent Transportation Systems, Policy formulation, Research product deployment, Funding,. System performance ... vehicles and among different vehicles (c) data ... plan and the use of traffic analysis tools to assist in evaluating ...

  20. Nanoscale electron transport at the surface of a topological insulator

    Science.gov (United States)

    Bauer, Sebastian; Bobisch, Christian A.

    2016-01-01

    The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless transport of electrons at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the electronic transport. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role. PMID:27098939

  1. Nanoscale electron transport at the surface of a topological insulator

    Science.gov (United States)

    Bauer, Sebastian; Bobisch, Christian A.

    2016-04-01

    The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless transport of electrons at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the electronic transport. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role.

  2. TRANSPORT OF BICOMPONENT CONTAMINANT IN FREE-SURFACE WETLAND FLOW

    Institute of Scientific and Technical Information of China (English)

    CHEN Bin; ZENG Li; WU Yi-hong; JI Ping; ZHAO Yi-jun

    2012-01-01

    This paper presents a theoretical analysis of a pulsed bicomponent contaminant emission into a free-surface wetland flow.The basic equations are for the bicomponent contaminant transport in the wetland flow under the combined action of advection,mass dispersion,and ecological reaction at the phase averaged scale.The effect of the ecological reaction is separated from the hydrodynamic effect via a set of widely used transforms.The analytical solution for the evolution of the depth-averaged concentration is rigorously derived,with a limiting case covering the known solution for the single component contaminant transport.It is found that the depth-averaged species concentration of the bicomponent contaminant can approach an equilibrium state determined by the distribution coefficient.

  3. Rapid transport from the surface to wells in fractured rock: a unique infiltration tracer experiment.

    Science.gov (United States)

    Levison, Jana K; Novakowski, Kent S

    2012-04-01

    A unique infiltration tracer experiment was performed whereby a fluorescent dye was applied to the land surface in an agricultural field, near Perth, Ontario, Canada, to simulate the transport of solutes to two pumped monitoring wells drilled into the granitic gneiss aquifer. This experiment, interpreted using the discrete-fracture capability of the numerical model HydroGeoSphere, showed that solute transport from the surface through thin soil (less than 2m) to wells in fractured bedrock can be extremely rapid (on the order of hours). Also, it was demonstrated that maximum concentrations of contaminants originating from the ground surface will not necessarily be the highest in the shallow aquifer horizon. These are important considerations for both private and government-owned drinking water systems that draw water from shallow fractured bedrock aquifers. This research illustrates the extreme importance of protecting drinking water at the source.

  4. Modeling marine surface microplastic transport to assess optimal removal locations

    Science.gov (United States)

    Sherman, Peter; van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres.

  5. Research on the Logistics Supply Chain in Port Logistics Transportation

    Directory of Open Access Journals (Sweden)

    Wang Yan-liang

    2013-11-01

    Full Text Available The aim of this study is to improve and increase the logistics system effectiveness and to solve the problem of optimal movement of different flows. Logistics transport carrying the world on material resources transfer exchange important mission and economic development and our lives are closely linked, logistics chain logistics transport occupies an important position and in the e logistics chain in port logistics has play a decisive role. For many coastal countries port logistics is the economic lifeline of the country, on China's economic development role as important, port logistics transport bear the material exchange with the external communication of important role, so the Chinese port logistics transportation research, clear port logistics transportation, current situation, find the existing problems in the light of the problem, to find a suitable method for solving has great realistic meaning. To promote logistics development, improve the logistics supply chain system has play an important role in this filed.

  6. Influence of enterococcal surface protein (esp) on the transport of Enterococcus faecium within saturated quartz sands.

    Science.gov (United States)

    Johanson, Jennifer J; Feriancikova, Lucia; Xu, Shangping

    2012-02-07

    Enterococcus was selected by US EPA as a Gram-positive indicator microorganism for groundwater fecal contamination. It was recently reported that enterococcal surface protein (esp) was more prevalent in Enterococcus from human sources than in Enterococcus from nonhuman sources and esp could potentially be used as a source tracking tool for fecal contamination (Scott et al., 2005). In this research, we performed laboratory column transport experiments to investigate the transport of Enterococcus faecium within saturated quartz sands. Particularly, we used a wild type strain (E1162) and a mutant (E1162Δesp) to examine the influence of esp on the transport behavior of E. faecium. Our results showed that esp could significantly enhance the attachment of E. faecium cells onto the surface of silica sands and thus lower the mobility of E. faecium within sand packs. Cell surface properties (e.g., zeta potential) were determined and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was applied to explain the effects of esp on the retention of E. faecium. Overall, our results suggested that E. faecium strains with esp could display lower mobility within saturated sand packs than E. faecium strains without esp. The disparity in the transport behavior of E. faecium with and without esp could limit the effectiveness of esp as a source tracking tool within the groundwater system.

  7. Ab initio transport across bismuth selenide surface barriers

    KAUST Repository

    Narayan, Awadhesh

    2014-11-24

    © 2014 American Physical Society. We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi2Se3(111) topological surface states by means of large-scale ab initio transport simulations. Our results demonstrate the suppression of perfect backscattering, while all other scattering processes, which do not entail a complete spin and momentum reversal, are allowed. Furthermore, we find that the spin of the surface state develops an out-of-plane component as it traverses the barrier. Our calculations reveal the existence of quasibound states in the vicinity of the surface barriers, which appear in the form of an enhanced density of states in the energy window corresponding to the topological state. For double barriers we demonstrate the formation of quantum well states. To complement our first-principles results we construct a two-dimensional low-energy effective model and illustrate its shortcomings. Our findings are discussed in the context of a number of recent experimental works.

  8. Impact of lux gene insertion on bacterial surface properties and transport.

    Science.gov (United States)

    Chen, Gang; Srinivasa Ranga, Vijay Penagonda; Mao, Yongjun; Chen, Kevin; Qiao, Hanzi

    2008-03-01

    Genetic markers have been in popular use for tracing microbial movement in the environment. However, the impact of genetic marker insertion on microbial surface properties and consequent transport is often ignored. For this research, we investigated the impact of luminescence-based genetic marker insertion on bacterial surface properties and transport. Typical Gram-positive bacterial strains of Lactobacillus casei, Streptococcus mitis and Micrococcus luteus were used as model bacterial strains in this research. We manipulated gene transfer to observe the impact of lux gene insertion on bacterial surface properties based on contact angle measurements, and we conducted column experiments to evaluate the impact of lux gene insertion on bacterial transport. After lux gene insertion, bacterial interactions with the porous media increased, demonstrating stronger deposition potential in the porous media. Accordingly, retention of the daughter strains increased. Lux gene insertion also resulted in an increase in bacterial dispersion and equilibrium adsorption in the porous media. The bacterial deposition coefficient was found to correlate with the free energy of interactions between bacteria and the porous media.

  9. Joint University Program for Air Transportation Research, 1986

    Science.gov (United States)

    Morrell, Frederick R. (Compiler)

    1988-01-01

    The research conducted under the NASA/FAA sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA and the FAA, one each with the Mass. Inst. of Tech., Ohio Univ., and Princeton Univ. Completed works, status reports, and bibliographies are presented for research topics, which include computer science, guidance and control theory and practice, aircraft performance, flight dynamics, and applied experimental psychology. An overview of activities is presented.

  10. Human behavior research and the design of sustainable transport systems

    Science.gov (United States)

    Schauer, James J.

    2011-09-01

    reduced carbon emissions are central to the design and optimization of future low carbon transport systems. Gaker et al (2011) suggest a framework, and provide insight into the willingness of transport consumers to pay for emission reductions of carbon dioxide from their personal transport choices within the context of other attributes of transport variables. The results of this study, although limited to a small demographic segment of the US population, demonstrate that people can integrate information on greenhouse gas emissions with other transport attributes including cost and time. Likewise, the research shows that the study group was willing to pay for reduction in greenhouse gas emissions associated with their transport choices. The study examined auto purchase choice, transport mode choice and transport route choice, which represent key decisions associated with transport that impact greenhouse gas emissions. Interestingly, they found that the study group was willing to pay for reductions in greenhouse gas emissions at a relatively consistent price across these transport choices. Clearly, the study results may not broadly apply to all demographics of users of transport, even in the study domain, due to the small demographic segment that was examined and the fact that the study was conducted in the laboratory. However, the methods used by Gaker et al (2011) are cause for optimism that future studies can obtain much needed mapping of transport preferences and willingness to pay for greenhouse gas emission reductions associated with personal transport choices. Although the Gaker et al (2011) study is directed at understanding the promotion of low carbon transport in the context of existing infrastructures, the ability of these studies to elucidate human behavior and preferences within the trade-offs of transport are critical to the design of future transport systems that seek to meet transport demand with constrained greenhouse gas emissions. Additional studies of

  11. Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport

    Science.gov (United States)

    Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.

    2002-12-01

    The physical, chemical, and biological controls on contaminant mobilities in aquatic ecosystems must be determined to establish the threat that contamination poses to the environment. Quantitative models of contaminant mobilities are required as a prerequisite to guide remediation efforts and to prioritize the potential hazard to the ecosystem of each contaminated site. It is well established that mineral surface adsorption is an important control on contaminant mobilities, and many studies have utilized thermodynamics to quantify metal/organic adsorption in order to yield predictive models of contaminant transport. However, these models of contaminant transport may not be representative of the reactions which control contaminant mobilities as most mineral surfaces are coated with organic acids, bacteria, and extracellular polymers. Numerous laboratory studies have demonstrated that bacterial cell walls have a high affinity for binding metal cations, and field studies indicate that a significant proportion of bacteria cells and associated extracellular matrices are coated with small scale hydrous metal oxides. The small size of bacteria, and in many cases the nanoscale of their associated mineral phases, suggests these bacteria-mineral composites may represent a large proportion of surface area exposed to fluid flow. Therefore, due to the affinity of bacterial cell walls for cations and biominerals, bacteria may also have a significant impact on anionic contaminant mobility in many natural systems. The extent of metal-bacteria adsorption reactions varies drastically as a function of pH and solution chemistry. Current adsorption models have focused on the interactions of positively charged metal cations with bacterial surfaces, however in many oxidizing environments metals such as Cr exist as anions or anionic complexes. We have studied the ability of non-metabolizing cells of the bacterial species Bacillus subtilis and Shewanella putrifaciens to adsorb aqueous Cr

  12. Main academic institutions conducting research in the public transport area

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, B.E. [Lund Inst. of Tech. (Sweden). Dept. of Traffic Planning and Engineering

    1997-12-01

    The international exchange of knowledge is becoming increasingly important for all activities. Within Europe, the need for simple reviews of institutions within one and the same subject area has become more tangible since the European Union started its public transport research program. The survey has been carried out in two stages. First a questionnaire was sent to those institutions, public transport authorities, public transport associations and individuals within the subject area that were known to the Department. In this questionnaire we asked for the names and addresses of institutions at colleges and universities where significant research on public transport is carried out. In a second stage, a list was compiled of the 48 institutions that were named in the results of the first questionnaire. This list was sent to these institutions with the request for a brief presentation of their research within the public transport sector and information on any institution they felt were missing in the list. We found further interesting institutions on the Internet. The final list contains more than 60 institutions outside the Nordic area. Within the Nordic countries we have exclusively followed our own address list of institutions with long-term research work within the subject area

  13. Harnessing innovation in passenger transport research in Africa

    CSIR Research Space (South Africa)

    Mokonyama, Mathetha T

    2006-07-01

    Full Text Available The paper provides the framework proposed by the newly established Built Environment Unit of CSIR, a public institution, to provide foresight driven research input into the passenger transport domain. This is modelled on the mandate of the CSIR...

  14. 36 CFR 13.460 - Use of snowmobiles, motorboats, dog teams, and other means of surface transportation...

    Science.gov (United States)

    2010-07-01

    ... transportation in accordance with 43 CFR 36.11(c), (d), (e), and (g). ..., motorboats, dog teams, and other means of surface transportation traditionally employed by local rural... of snowmobiles, motorboats, dog teams, and other means of surface transportation...

  15. Surface trap mediated electronic transport in biofunctionalized silicon nanowires

    Science.gov (United States)

    Puppo, F.; Traversa, F. L.; Di Ventra, M.; De Micheli, G.; Carrara, S.

    2016-08-01

    Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface electronic transport in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I-V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I-V characteristics in other nanostructured devices, for different than antibody-based sensing as well as electronic applications.

  16. Research on gas transport in chimneys: a progress report

    Energy Technology Data Exchange (ETDEWEB)

    Hearst, J.R.

    1986-03-18

    The results of the AGRINI and TIERRA experiments have led us to study three general topics: collapse phenomenology, CO/sub 2/ content measurement, and gas transport in chimneys. Our results so far are fragmentary, but we have been able to come to some tentative conclusions: (1) a layer of strong material between depths of 24 and 32 m, and perhaps some relatively strong material deeper, may have caused the AGRINI crater shape. This layer was absent at the nearby LABAN and CROWDIE events. We were unable to locate the layer with a surface penetrometer or surface seismic methods, but it may be possible to measure strength vs depth in situ by examining the penetration depth of a projectile. (2) We can probably improve our knowledge of the in situ CO/sub 2/ content by calibrating a commercial carbon/oxygen logging system for NTS conditions. (3) It is possible to measure the response of the gas in a chimney to changes in atmospheric pressure. There can be significantly different gas transport in chimneys with the same pressure response, depending on the porosity and the distribution of the porosity. It is possible to perform an inexpensive experiment to study the gas transport in an existing chimney.

  17. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    NARCIS (Netherlands)

    Bhattacharjee, S.; Opstal, van E.J.; Alink, G.M.; Marcelis, A.T.M.; Zuilhof, H.; Rietjens, I.M.C.M.

    2013-01-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/s

  18. Research and development of electric vehicles for clean transportation.

    Science.gov (United States)

    Wada, Masayoshi

    2009-01-01

    This article presents the research and development of an electric vehicle (EV) in Department of Human-Robotics Saitama Institute of Technology, Japan. Electric mobile systems developed in our laboratory include a converted electric automobile, electric wheelchair and personal mobile robot. These mobile systems contribute to realize clean transportation since energy sources and devices from all vehicles, i.e., batteries and electric motors, does not deteriorate the environment. To drive motors for vehicle traveling, robotic technologies were applied.

  19. The effects of surface aging on nanoparticle fate and transport in natural and engineered porous media

    Science.gov (United States)

    Mittelman, Anjuliee M.

    Nanomaterials will be subjected to various surface transformations in the environment and within water and wastewater treatment systems. A comprehensive understanding of the fate and transport behavior of "aged" nanomaterials in both natural and engineered porous media is required in order to accurately quantify ecological and human health risks. This research sought to (1) evaluate the impact of ultraviolet (UV) light aging on nanoparticle transport in water-saturated porous media; and (2) assess the effects of influent water quality on silver nanoparticle retention and dissolution in ceramic water filters. Additionally, the value of quartz crystal microbalance (QCM-D) data in nanoparticle fate and transport studies was evaluated by comparing deposition behavior in complementary QCM-D and sand columns experiments. Silver (nAg) and iron oxide nanoparticles exposed to UV light were up to 50% more strongly retained in porous media compared with freshly prepared suspensions due to less negative surface charge and larger aggregate sizes. UV-aged nAg were more prone to dissolution in sand columns, resulting in effluent Ag+ concentrations as high as 1.2 mg/L. In ceramic water filters, dissolution and cation exchange processes controlled silver release into treated water. The use of acidic, high salinity, or high hardness water accelerated oxidative dissolution of the silver coating and resulted in effluent silver concentrations 5-10 times above international drinking water guidelines. Results support the recommendation for a regular filter replacement or silver re-application schedule to ensure ongoing efficacy. Taken in concert, these research findings suggest that oxidative aging of nanomaterial surfaces (either through exposure to UV light or aggressive water chemistries) will alter the fate of nanomaterials in the environment and may decrease the effective lifetime of devices which utilize nanotechnology. Corresponding QCM-D and column experiments revealed that

  20. Predicting Solar Cycle 25 using Surface Flux Transport Model

    Science.gov (United States)

    Imada, Shinsuke; Iijima, Haruhisa; Hotta, Hideyuki; Shiota, Daiko; Kusano, Kanya

    2017-08-01

    It is thought that the longer-term variations of the solar activity may affect the Earth’s climate. Therefore, predicting the next solar cycle is crucial for the forecast of the “solar-terrestrial environment”. To build prediction schemes for the next solar cycle is a key for the long-term space weather study. Recently, the relationship between polar magnetic field at the solar minimum and next solar activity is intensively discussed. Because we can determine the polar magnetic field at the solar minimum roughly 3 years before the next solar maximum, we may discuss the next solar cycle 3years before. Further, the longer term (~5 years) prediction might be achieved by estimating the polar magnetic field with the Surface Flux Transport (SFT) model. Now, we are developing a prediction scheme by SFT model as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction) and adapting to the Cycle 25 prediction. The predicted polar field strength of Cycle 24/25 minimum is several tens of percent smaller than Cycle 23/24 minimum. The result suggests that the amplitude of Cycle 25 is weaker than the current cycle. We also try to obtain the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters will be used in the SFT models to predict the polar magnetic fields strength at the solar minimum. In this presentation, we will explain the outline of our strategy to predict the next solar cycle and discuss the initial results for Cycle 25 prediction.

  1. Evaluation of KFB-funded research on transport systems

    Energy Technology Data Exchange (ETDEWEB)

    Boyce, D.; Knudsen, T.; Wegener, M.

    1999-09-01

    This report presents an evaluation of two research projects on transport systems, which have been financed fully or partially by KFB. The projects are: l. Systems analysis of transport markets at the Division of Transport and Location Analysis in the Department of Infrastructure and Planning of the Royal Institute of Technology, Stockholm; and 2. Planning, analysis and management in traffic networks - optimization models and methods at the Division of Optimization in the Department of Mathematics at Linkoeping University. The evaluation seeks to examine the scientific quality of the research and its relevance to the academic world and society. The two project teams prepared a self-assessment of their research activities and submitted copies of relevant publications. The evaluation committee visited both institutions and engaged the teams in discussions of their results and methodology. These visits occurred on June 1 and 2, 1999. This report is based on the self-assessments of the teams, the materials submitted and the meetings with the project teams. The evaluation and recommendations presented in the report are those of the reviewers and do not necessarily represent the views of KFB

  2. Automatic braking system modification for the Advanced Transport Operating Systems (ATOPS) Transportation Systems Research Vehicle (TSRV)

    Science.gov (United States)

    Coogan, J. J.

    1986-01-01

    Modifications were designed for the B-737-100 Research Aircraft autobrake system hardware of the Advanced Transport Operating Systems (ATOPS) Program at Langley Research Center. These modifications will allow the on-board flight control computer to control the aircraft deceleration after landing to a continuously variable level for the purpose of executing automatic high speed turn-offs from the runway. A bread board version of the proposed modifications was built and tested in simulated stopping conditions. Test results, for various aircraft weights, turnoff speed, winds, and runway conditions show that the turnoff speeds are achieved generally with errors less than 1 ft/sec.

  3. Laboratory studies of aeolian sediment transport processes on planetary surfaces

    Science.gov (United States)

    Rasmussen, Keld R.; Valance, Alexandre; Merrison, Jonathan

    2015-09-01

    , but not all, older or recent wind tunnel observations. Similarly some measurements performed with uniform sand samples having grain diameters of the order of 0.25-0.40 mm indicate that ripple spacing depends on friction velocity in a similar way as particle jump length. The observations are thus in agreement with a recent ripple model that link the typical jump length to ripple spacing. A possible explanation for contradictory observations in some experiments may be that long observation sequences are required in order to assure that equilibrium exists between ripple geometry and wind flow. Quantitative understanding of saltation characteristics on Mars still lacks important elements. Based upon image analysis and numerical predictions, aeolian ripples have been thought to consist of relatively large grains (diameter > 0.6 mm) and that saltation occurs at high wind speeds (> 26 m/s) involving trajectories that are significantly longer than those on Earth (by a factor of 10-100). However, this is not supported by recent observations from the surface of Mars, which shows that active ripples in their geometry and composition have characteristics compatible with those of terrestrial ripples (Sullivan et al., 2008). Also the highest average wind speeds on Mars have been measured to be terrestrial conditions electric fields typically observed are not intense enough to significantly affect sand transport rates while little is known in the case of extra-terrestrial environments.

  4. Large scale reactive transport of nitrate across the surface water divide

    Science.gov (United States)

    Kortunov, E.; Lu, C.; Amos, R.; Grathwohl, P.

    2016-12-01

    Groundwater pollution caused by agricultural and atmospheric inputs is a pressing issue in environmental management worldwide. Various researchers have studied different aspects of nitrate contamination since the substantial increase of the agriculture pollution in the second half of the 20th century. This study addresses large scale reactive solute transport in a typical Germany hilly landscapes in a transect crossing 2 valleys: River Neckar and Ammer. The numerical model was constructed compromising a 2-D cross-section accounting for typical fractured mudstones and unconsolidated sediments. Flow modelling showed that the groundwater divide significantly deviates from the surface water divide providing conditions for inter-valley flow and transport. Reactive transport modelling of redox-sensitive solutes (e.g. agriculture nitrate and natural sulfate, DOC, ammonium) with MIN3P was used to elucidate source of nitrate in aquifers and rivers. Since both floodplains, in the Ammer and Neckar valley contain Holocene sediments relatively high in organic carbon, agricultural nitrate is reduced therein and does not reach the groundwater. However, nitrate applied in the hillslopes underlain by fractured oxidized mudrock is transported to the high yield sand and gravel aquifer in the Neckar valley. Therefore, the model predicts that nitrate in the Neckar valley comes, to a large extent, from the neighboring Ammer valley. Moreover, nitrate observed in the rivers and drains in the Ammer valley is very likely geogenic since frequent peat layers there release ammonium which is oxidized as it enters the surface water. Such findings are relevant for land and water quality management.

  5. Importance of 3D Processes Near the Ocean's Surface for Material Transport

    Science.gov (United States)

    Ozgokmen, T. M.

    2014-12-01

    There are a number of practical problems that demand an accurate knowledge of ocean currents near the surface of the ocean. It is known that oceanic coherent features transport heat and carry out vertical exchange of biogeochemical tracers. Ocean currents can affect biological primary production, air-sea gas exchanges and global tracer budgets. Ocean currents are also important for the dispersion of substances that pose a danger to society, economy and human health. Examples of such events include algal blooms, the Fukushima nuclear plant incident in the Pacific Ocean in 2011, and repeated large oil spills in the Gulf of Mexico, namely the IXTOC in 1978 and the Deepwater Horizon event in 2010. Such incidents demand accurate answers to questions such as ``where will the pollutant go?", ``how fast will it get there?" and ``how much pollutant will arrive there?", and in some instances ``where did the pollutant come from?". The answers to these questions are critical to the allocation of limited response resources, and in determining the overall impact of the events. We will summarize the efforts by the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE). One of the primary objectives of CARTHE is to improve predictive modeling capability for flows near the air-sea interface. In particular, two large experiments, Grand Lagrangian Deployment (GLAD) and Surf-zone and Coastal Oil Pathways Experiment (SCOPE), coordinated with real-time modeling were instructive on processes influencing near-surface material transport. Findings on submesoscale flows as well as model deficiencies to capture processes relevant to transport will be discussed. Insight into future modeling and observational plans will be provided.

  6. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging

    CERN Document Server

    Shocron, Amit N

    2016-01-01

    Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated. While at some model conditions surface transport enhances the rate of CDI cell charging, counter-intuitively this additional transport pathway is found to slow down cell charging at other model conditions.

  7. Surface electronic transport measurements: A micro multi-point probe approach

    DEFF Research Database (Denmark)

    Barreto, Lucas

    2014-01-01

    setup, but the terminology used and data analysis were also ameliorated in order to simplify the interpretation of the results. We used the mentioned technique in the following projects: • The electronic transport dimensionality of epitaxial grahene grown on SiC is detected and important physical......This work is mostly focused on the study of electronic transport properties of two-dimensional materials, in particular graphene and topological insulators. To study these, we have improved a unique micro multi-point probe instrument used to perform transport measurements. Not only the experimental...... a direct measurement of the surface electronic transport on a bulk topological insulator. The surface state conductivity and mobility are obtained. Apart from transport properties, we also investigate the atomic structure of the Bi2Se3(111) surface via surface x-ray diraction and low-energy electron...

  8. Applying GIS characterizing and modeling contaminant transport in surface water at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Becker, N.M.; Van Eeckhout, E. [Los Alamos National Lab., NM (United States); David, N.A. [Environmental Res., Inst. of Michigan, Santa Fe, NM (United States); Irvine, J.M. [Environmental Res. Inst. of Michigan, Arlington, VA (United States)

    1995-10-01

    During World War II, Los Alamos, New Mexico was chosen as the site for the secret development of the first atomic bomb. The remote location in the southwestern United States was ideal for such a project. After the war, research activities continued at the Los Alamos installation, focusing on new nuclear weapons models as well as greater effectiveness and reliability of existing weapons. Due to the emphasis on nuclear and non-nuclear weapons development as well as associated nuclear research, a large inventory of radionuclides and heavy metals have been tested, expended, and disposed of in the local environment, a high plateau of tuffaceous volcanic rocks incised by deep canyons in a semi-arid climate. In recent years an intensive evaluation of the environmental, impact of weapons testing at Los Alamos and elsewhere has been undertaken. GIS system utilization and image processing of past and current data has been an important part of this evaluation. Important problems can be more easily displayed and understood using this methodology. The main objective in this paper is to illustrate how transport of depleted uranium and associated heavy metals (copper in this case) used in dynamic testing of weapons components at open air firing sites can be evaluated and visualized. In our studies, surface water has been found to be the predominant transport mechanism. We have sampled soils, sediments, fallout, runoff water and snowmelt over a number of years in order to understand contaminant transport on- and offsite. Statistical analyses of these data have assisted in our characterization of issues such as contaminant variability, spatially and temporally, as well as in development of transport rates.

  9. Research and development of electric vehicles for clean transportation

    Institute of Scientific and Technical Information of China (English)

    WADA Masayoshi

    2009-01-01

    This article presents the research and development of an electric vehicle (EV) in Dept.of Human-Robotics Saitama Institute of Technology.Electric mobile systems developed in our laboratory include a converted electric automobile,electric wheelchair and personal mobile robot.These mobile systems contribute to realize clean transportation since energy sources and devices from all vehicles,i.e.,batteries and electric motors,does not deteriorate the environment.To drive motors for vehicle traveling,robotic technologies were applied.

  10. Research on ultrasonic detection of complex surfaces

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Parts of complex surface are widely used now in many fields, and their detection has caused much concern. In China many manufactories still carry on the traditional way of manual detection, which requires highly skilled personnel and efficiency is low. Some large manufactories have imported auto-detecting equipments, which require CAD data on the parts, or just divide the surface into several approximate planes for automatic detection. Phased-array system is seldom used, and the cost is high. Besides,most of the systems have not considered the automatic sensitivity compensation of parts with varying thickness. To improve the detection quality and efficiency of nondestructive test (NDT) of parts of complex surface, this paper puts forward an integrated ultrasonic NDT system characterized by: (1) Use of ultrasonic measurement and reverse of curved surface to solve the CAD data problem; (2) Use of an automatic sensitivity compensation algorithm (based on the part's modelling information obtained in surface reverse) to fit the variety of the thickness; (3) Use of template matching and pseudo-color imaging to improve the quality of detection results. The system features integration of low cost mature technologies, and is suitable for detection of various parts of different complex surfaces in medium-and-small enterprises. The test results showed that the system can automatically detect parts of complex surface successfully, and that the inspection result is good and reliable.

  11. Sea Surface Salinity : Research Challenges and Opportunities

    Science.gov (United States)

    Halpern, David; Lagerloef, Gary; Font, Jordi

    2012-01-01

    Sea surface salinity (SSS) can be important in regulating sea surface temperature (SST). Two technological breakthrough satellite SSS missions, Aquarius and Soil Moisture and Ocean Salinity (SMOS), are currently producing high-quality SSS data. This paper provides an overview of the importance of SSS for weather and climate applications and describes the Aquarius and SMOS missions. The newness of adequately sampled SSS data prompted a first-time at-sea field campaign devoted to improved understanding of SSS variations.

  12. The Small Aircraft Transportation System (SATS): Research Collaborations with the NASA Langley Research Center

    Science.gov (United States)

    Tarry, Scott E.; Bowen, Brent D.; Nickerson, Jocelyn S.

    2002-01-01

    The aviation industry is an integral part of the world s economy. Travelers have consistently chosen aviation as their mode of transportation as it is reliable, time efficient and safe. The out- dated Hub and Spoke system, coupled with high demand, has led to delays, cancellations and gridlock. NASA is developing innovative solutions to these and other air transportation problems. This research is being conducted through partnerships with federal agencies, industry stakeholders, and academia, specifically the University of Nebraska at Omaha. Each collaborator is pursuing the NASA General Aviation Roadmap through their involvement in the expansion of the Small Aircraft Transportation System (SATS). SATS will utilize technologically advanced small aircraft to transport travelers to and from rural and isolated communities. Additionally, this system will provide a safe alternative to the hub and spoke system, giving more time to more people through high-speed mobility and increased accessibility.

  13. Transportable Hydrogen Research Plant Based on Renewable Energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikel Fernandez; Carlos Madina; Asier Gil de Muro [LABEIN, Parque Tecnologico, edificio 700, 48160 Derio, Bizkaia (Spain); Jose Angel Alzolab; Iker Marino; Javier Garcia-Tejedor [ROBOTIKER, Parque Tecnologico, edificio 202, 48170 Zamudio, Bizkaia, (Spain); Juan Carlos Mugica; Inaki Azkkrate; Jose Angel Alzola [INASMET, Mikeletegi Pasalekua, Parque Tecnologico, E-20009 San Sebastian, Guipuzcoa (Spain)

    2006-07-01

    Efficiency and cost are nowadays the most important barriers for the penetration of systems based on hydrogen and renewable energies. According to this background, TECNALIA Corporation has started in 2004 the HIDROTEC project: 'Hydrogen Technologies for Renewable Energy Applications'. The ultimate aim of this project is the implementation of a multipurpose demonstration and research plant in order to explore diverse options for sustainable energetic solutions based on hydrogen. The plant is conceived as an independent system that can be easily transported and assembled. Research and demonstration activities can thus be carried out at very different locations, including commercial renewable facilities. Modularity and scalability have also been taken into account for an optimised exploitation. (authors)

  14. Vehicle Emission Inspection and Maintenance (I/M) Provision in the Fixing America’s Surface Transportation (FAST) Act

    Science.gov (United States)

    This document is a memorandum regarding Vehicle Emission Inspection and Maintenance (I/M) Provision in Fixing America's Surface Transportation (FAST) Act, which provides long-term funding certainty for surface transportation infrastructure planning

  15. On Limiting Behavior of Contaminant Transport Models in Coupled Surface and Groundwater Flows

    Directory of Open Access Journals (Sweden)

    Vincent J. Ervin

    2015-11-01

    Full Text Available There has been a surge of work on models for coupling surface-water with groundwater flows which is at its core the Stokes-Darcy problem. The resulting (Stokes-Darcy fluid velocity is important because the flow transports contaminants. The analysis of models including the transport of contaminants has, however, focused on a quasi-static Stokes-Darcy model. Herein we consider the fully evolutionary system including contaminant transport and analyze its quasi-static limits.

  16. Serotonin-induced down-regulation of cell surface serotonin transporter

    DEFF Research Database (Denmark)

    Jørgensen, Trine Nygaard; Christensen, Peter Møller; Gether, Ulrik

    2014-01-01

    The serotonin transporter (SERT) terminates serotonergic signaling and enables refilling of synaptic vesicles by mediating reuptake of serotonin (5-HT) released into the synaptic cleft. The molecular and cellular mechanisms controlling SERT activity and surface expression are not fully understood...

  17. 75 FR 9638 - Surface Transportation Project Delivery Pilot Program; Caltrans Audit Report

    Science.gov (United States)

    2010-03-03

    ...; 49 CFR 1.48. Issued on: February 23, 2010. Victor M. Mendez, Administrator. Surface Transportation... Chapter 25 references FHWA Order 6640.2 FHWA Actions to address Environmental Justice in minority and...

  18. Transport Rate of Surface Erosion by the Hydrodynamics

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The coherence and exposure degree are used in analyzing initiation of slope sediment.The initial ve- locity is built by using a critical roiling model.A transport rate formula of slope erosion is established using the Meyer-Peter model.The formula is tested by experiment and agrees well but the errors are big when the flow discharge and rain intensity are smaller.

  19. Enhanced Thermal Transport of Surfaces with Superhydrophobic Coatings

    Science.gov (United States)

    2015-07-01

    Deposition 4 3. Results/ Analysis 5 4. Conclusion 7 5. References 8 Distribution List 9 iv List of Figures Fig. 1 Contact angle...by measuring the contact angle (σ) formed between a droplet of liquid and the surface (Fig. 1). Qualitatively , surfaces with a water contact angle...several seconds and dried with filtered nitrogen. The samples were then immersed in 0.01-M aqueous solution of silver nitrate for 20 s. The deposition

  20. Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer

    Directory of Open Access Journals (Sweden)

    C. Wegner

    2012-09-01

    Full Text Available Sediment transport dynamics were studied during ice-free conditions under different atmospheric circulation regimes on the Laptev Sea shelf (Siberian Arctic. To study the interannual variability of suspended particulate matter (SPM dynamics and their coupling with the variability in surface river water distribution on the Laptev Sea detailed oceanographic, optical (turbidity and Ocean Color satellite data, and hydrochemical (nutrients, SPM, stable oxygen isotopes process studies were carried out continuously during the summers of 2007 and 2008. Thus, for the first time SPM and nutrient variations on the Laptev Sea shelf under different atmospheric forcing and the implications for the turbidity and transparency of the water column can be presented.

    The data indicate a clear link between different surface distributions of riverine waters and the SPM transport dynamics within the entire water column. The summer of 2007 was dominated by shoreward winds and an eastward transport of riverine surface waters. The surface SPM concentration on the south-eastern inner shelf was elevated, which led to decreased transmissivity and increased light absorption. Surface SPM concentrations in the Central and Northern Laptev Sea were comparatively low. However, the SPM transport and concentration within the bottom nepheloid layer increased considerably on the entire eastern shelf. The summer of 2008 was dominated by offshore-winds and northwards transport of the river plume. The surface SPM transport was enhanced and extended onto the mid-shelf whereas the bottom SPM transport and concentration was diminished. This study suggests that the SPM concentration and transport in both, the surface and bottom nepheloid layers, are associated with the distribution of riverine surface waters which are linked to the atmospheric circulation patterns over the Laptev Sea and the adjacent Arctic Ocean during open water season. A continuing trend toward shoreward winds

  1. Integration of inland waterway transport in the intermodal supply chain: a taxonomy of research challenges

    OpenAIRE

    Caris, An; Limbourg, Sabine; Macharis, Cathy; Van Lier, Tom; Cools, Mario

    2014-01-01

    This paper identifies research opportunities which will enable the further integration of inland waterway transport in the intermodal supply chain. Intermodal transport may be interpreted as a chain of actors who supply a transport service. Inland navigation can play a crucial role in increasing supply chain service performance. A first group of research challenges lies in the evolving relationship between transport geography and logistics activities. The next set of research challenges has t...

  2. Some results from 50 years' research on surface forces

    Science.gov (United States)

    Derjaguin, B. V.

    1992-05-01

    A review is presented about research on surface forces and surface interactions conducted over the past half-century, with some emphasis on the pioneering contributions of the Department of Surface Phenomena at the Institute of Physical Chemistry of the USSR Academy of Sciences.

  3. Surface barrier research at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Gee, G.W.; Ward, A.L.; Fayer, M.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-12-31

    At the DOE Hanford Site, a field-scale prototype surface barrier was constructed in 1994 over an existing waste site as a part of a CERCLA treatability test. The above-grade barrier consists of a fine-soil layer overlying coarse layers of sands, gravels, basalt rock (riprap), and a low permeability asphalt layer. Two sideslope configurations, clean-fill gravel on a 10:1 slope and basalt riprap on a 2:1 slope, were built and are being tested. Design considerations included: constructability; drainage and water balance monitoring, wind and water erosion control and monitoring; surface revegetation and biotic intrusion; subsidence and sideslope stability, and durability of the asphalt layer. The barrier is currently in the final year of a three-year test designed to answer specific questions related to stability and long-term performance. One half of the barrier is irrigated such that the total water applied, including precipitation, is 480 mm/yr (three times the long-term annual average). Each year for the past two years, an extreme precipitation event (71 mm in 8 hr) representing a 1,000-yr return storm was applied in late March, when soil water storage was at a maximum. While the protective sideslopes have drained significant amounts of water, the soil cover (2-m of silt-loam soil overlying coarse sand and rock) has never drained. During the past year there was no measurable surface runoff or wind erosion. This is attributed to extensive revegetation of the surface. In addition, the barrier elevation has shown a small increase of 2 to 3 cm that is attributed to a combination of root proliferation and freeze/thaw activity. Testing will continue through September 1997. Performance data from the prototype barrier will be used by DOE in site-closure decisions at Hanford.

  4. Transportable Heavy Duty Emissions Testing Laboratory and Research Program

    Energy Technology Data Exchange (ETDEWEB)

    David Lyons

    2008-03-31

    The objective of this program was to quantify the emissions from heavy-duty vehicles operating on alternative fuels or advanced fuel blends, often with novel engine technology or aftertreatment. In the first year of the program West Virginia University (WVU) researchers determined that a transportable chassis dynamometer emissions measurement approach was required so that fleets of trucks and buses did not need to be ferried across the nation to a fixed facility. A Transportable Heavy-Duty Vehicle Emissions Testing Laboratory (Translab) was designed, constructed and verified. This laboratory consisted of a chassis dynamometer semi-trailer and an analytic trailer housing a full scale exhaust dilution tunnel and sampling system which mimicked closely the system described in the Code of Federal Regulations for engine certification. The Translab was first used to quantify emissions from natural gas and methanol fueled transit buses, and a second Translab unit was constructed to satisfy research demand. Subsequent emissions measurement was performed on trucks and buses using ethanol, Fischer-Tropsch fuel, and biodiesel. A medium-duty chassis dynamometer was also designed and constructed to facilitate research on delivery vehicles in the 10,000 to 20,000lb range. The Translab participated in major programs to evaluate low-sulfur diesel in conjunction with passively regenerating exhaust particulate filtration technology, and substantial reductions in particulate matter were recorded. The researchers also participated in programs to evaluate emissions from advanced natural gas engines with closed loop feedback control. These natural gas engines showed substantially reduced levels of oxides of nitrogen. For all of the trucks and buses characterized, the levels of carbon monoxide, oxides of nitrogen, hydrocarbons, carbon dioxide and particulate matter were quantified, and in many cases non-regulated species such as aldehydes were also sampled. Particle size was also

  5. Exploratory research into pathogen surface interactions.

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, Michael B.; Lane, Todd W. (Sandia National Laboratories, Livermore, CA); Jones, Howland D. T.; Rebeil, Roberto; Altman, Susan Jeanne; Kaiser, Julie (Sandia National Laboratories, Livermore, CA); McGrath, Lucas K.; Souza, Caroline Ann

    2006-02-01

    In this short-duration project the research team was able to achieve growth of both drinking water biofilms and monospecific biofilms of Legionella pneurnophila. Preliminary comparative proteomic analyses were carried out on planktonic and biofilm-associated Legionella. After delay for completion of permitting and review by the director of the National Institutes for Allergy and Infectious Disease, the Utah 112 strain of Francisella novicida was obtained and preliminary culture and comparative proteomic analyses were carried out. Comprehensive literature searches and data mining were carried out on all research topics.

  6. Hydrogen mediated transport of Sn to Ru film surface

    NARCIS (Netherlands)

    Faradzhev, N.; Sidorkin, V.

    2009-01-01

    The authors report on the interaction of atomic hydrogen with Sn and thin Ru film at room temperature. The study is done using a combination of photoelectron and low energy ion scattering spectroscopies as well as scanning electron microscopy. The adsorption of hydrogen on a Sn surface leads to the

  7. Hydrogen mediated transport of Sn to Ru film surface

    NARCIS (Netherlands)

    Faradzhev, N.; Sidorkin, V.

    2009-01-01

    The authors report on the interaction of atomic hydrogen with Sn and thin Ru film at room temperature. The study is done using a combination of photoelectron and low energy ion scattering spectroscopies as well as scanning electron microscopy. The adsorption of hydrogen on a Sn surface leads to the

  8. Transport mechanism of an initially spherical droplet on a combined hydrophilic/hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook; Kwon, Young Hoo [Dept. of Mechanical Engineering, Kookmin University, Seoul (Korea, Republic of)

    2015-11-15

    Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources, and numerically validated the results for a hypothetical 2D shape, initially having a hemicylindrical droplet shape. Myong and Kwon (2015) have also examined the transport mechanism for an actual water droplet, initially having a 3D hemispherical shape, on a horizontal hydrophilic/hydrophobic surface, based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, pressure and surface free energies inside the droplet. In this study, a 3D numerical analysis of an initially spherical droplet is carried out to establish a new concept for droplet transport. Further, the transport mechanism of an actual water droplet is examined in detail from the viewpoint of the capillarity force imbalance through the numerical results of droplet shape and various energies inside the droplet.

  9. 75 FR 24773 - Research and Innovative Technology Administration Advisory Council on Transportation Statistics...

    Science.gov (United States)

    2010-05-05

    ... Bureau of Transportation Statistics Research and Innovative Technology Administration Advisory Council on Transportation Statistics; Notice of Meeting AGENCY: Research and Innovative Technology Administration, U.S... on Transportation Statistics (ACTS). The meeting will be held on Friday, June 4, 2010, from 9 a.m....

  10. Modeling Fate and Transport of Rotavirus in Surface Flow by Integrating WEPP and a Pathogen Transport Model

    Science.gov (United States)

    Bhattarai, R.; Kalita, P. K.; Davidson, P. C.; Kuhlenschmidt, M. S.

    2012-12-01

    More than 3.5 million people die each year from a water related diseases in this world. Every 20 seconds, a child dies from a water-related illness. Even in a developed country like the United States, there have been at least 1870 outbreaks associated with drinking water during the period of 1920 to 2002, causing 883,806 illnesses. Most of these outbreaks are resulted due to the presence of microbial pathogens in drinking water. Rotavirus infection has been recognized as the most common cause of diarrhea in young children throughout the world. Laboratory experiments conducted at the University of Illinois have demonstrated that recovery of rotavirus has been significantly affected by climatic and soil-surface conditions like slope, soil types, and ground cover. The objective of this study is to simulate the fate and transport of Rotavirus in overland and near-surface flow using a process-based model. In order to capture the dynamics of sediment-bound pathogens, the Water Erosion Prediction Project (WEPP) is coupled with the pathogen transport model. Transport of pathogens in overland flow can be simulated mathematically by including terms for the concentration of the pathogens in the liquid phase (in suspension or free-floating) and the solid phase (adsorbed to the fine solid particles like clay and silt). Advection, adsorption, and decay processes are considered. The mass balance equations are solved using numerical technique to predict spatial and temporal changes in pathogen concentrations in two phases. Outputs from WEPP simulations (flow velocity, depth, saturated conductivity and the soil particle fraction exiting in flow) are transferred as input for the pathogen transport model. Three soil types and three different surface cover conditions have been used in the experimental investigations. Results from these conditions have been used in calibrating and validating the simulation results. Bare surface conditions have produced very good agreement between

  11. Spatial Transport of Magnetic Flux Surfaces in Strongly Anisotropic Turbulence

    Science.gov (United States)

    Matthaeus, W. H.; Servidio, S.; Wan, M.; Ruffolo, D. J.; Rappazzo, A. F.; Oughton, S.

    2013-12-01

    Magnetic flux surfaces afford familiar descriptions of spatial structure, dynamics, and connectivity of magnetic fields, with particular relevance in contexts such as solar coronal flux tubes, magnetic field connectivity in the interplanetary and interstellar medium, as well as in laboratory plasmas and dynamo problems [1-4]. Typical models assume that field-lines are orderly, and flux tubes remain identifiable over macroscopic distances; however, a previous study has shown that flux tubes shred in the presence of fluctuations, typically losing identity after several correlation scales [5]. Here, the structure of magnetic flux surfaces is numerically investigated in a reduced magnetohydrodynamic (RMHD) model of homogeneous turbulence. Short and long-wavelength behavior is studied statistically by propagating magnetic surfaces along the mean field. At small scales magnetic surfaces become complex, experiencing an exponential thinning. At large scales, instead, the magnetic flux undergoes a diffusive behavior. The link between the diffusion of the coarse-grained flux and field-line random walk is established by means of a multiple scale analysis. Both large and small scales limits are controlled by the Kubo number. These results have consequences for understanding and interpreting processes such as magnetic reconnection and field-line diffusion in plasmas [6]. [1] E. N. Parker, Cosmical Magnetic Fields (Oxford Univ. Press, New York, 1979). [2] J. R. Jokipii and E. N. Parker, Phys. Rev. Lett. 21, 44 (1968). [3] R. Bruno et al., Planet. Space Sci. 49, 1201 (2001). [4] M. N. Rosenbluth et al., Nuclear Fusion 6, 297 (1966). [5] W. H. Matthaeus et al., Phys. Rev. Lett. 75, 2136 (1995). [6] S. Servidio et al., submitted (2013).

  12. Electrical transport properties of graphene on SiO2 with specific surface structures

    OpenAIRE

    Nagashio, K.; Yamashita, T; Nishimura, T.; K. Kita; Toriumi, A.

    2011-01-01

    The mobility of graphene transferred on a SiO2/Si substrate is limited to ~10,000 cm2/Vs. Without understanding the graphene/SiO2 interaction, it is difficult to improve the electrical transport properties. Although surface structures on SiO2 such as silanol and siloxane groups are recognized, the relation between the surface treatment of SiO2 and graphene characteristics has not yet been elucidated. This paper discusses the electrical transport properties of graphene on specific surface stru...

  13. Interplay between hydrophilicity and surface barriers on water transport in zeolite membranes

    Science.gov (United States)

    Fasano, Matteo; Humplik, Thomas; Bevilacqua, Alessio; Tsapatsis, Michael; Chiavazzo, Eliodoro; Wang, Evelyn N.; Asinari, Pietro

    2016-10-01

    A comprehensive understanding of molecular transport within nanoporous materials remains elusive in a broad variety of engineering and biomedical applications. Here, experiments and atomistic simulations are synergically used to elucidate the non-trivial interplay between nanopore hydrophilicity and surface barriers on the overall water transport through zeolite crystals. At these nanometre-length scales, these results highlight the dominating effect of surface imperfections with reduced permeability on the overall water transport. A simple diffusion resistance model is shown to be sufficient to capture the effects of both intracrystalline and surface diffusion resistances, thus properly linking simulation to experimental evidence. This work suggests that future experimental work should focus on eliminating/overcoming these surface imperfections, which promise an order of magnitude improvement in permeability.

  14. Theory connecting nonlocal sediment transport, earth surface roughness, and the Sadler effect

    Science.gov (United States)

    Schumer, Rina; Taloni, Alessandro; Furbish, David Jon

    2017-03-01

    Earth surface evolution, like many natural phenomena typified by fluctuations on a wide range of scales and deterministic smoothing, results in a statistically rough surface. We present theory demonstrating that scaling exponents of topographic and stratigraphic statistics arise from long-time averaging of noisy surface evolution rather than specific landscape evolution processes. This is demonstrated through use of "elastic" Langevin equations that generically describe disturbance from a flat earth surface using a noise term that is smoothed deterministically via sediment transport. When smoothing due to transport is a local process, the geologic record self organizes such that a specific Sadler effect and topographic power spectral density (PSD) emerge. Variations in PSD slope reflect the presence or absence and character of nonlocality of sediment transport. The range of observed stratigraphic Sadler slopes captures the same smoothing feature combined with the presence of long-range spatial correlation in topographic disturbance.

  15. Wind-induced contaminant transport in near-surface soils with application to radon entry into buildings

    Energy Technology Data Exchange (ETDEWEB)

    Riley, W J [Univ. of California, Berkeley, CA (United States)

    1996-05-01

    Indoor air exposures to gaseous contaminants originating in soil can cause large human health risks. To predict and control these exposures, the mechanisms that affect vapor transport in near-surface soils need to be understood. In particular, radon exposure is a concern since average indoor radon concentrations lead to much higher risks than are generally accepted for exposure to other environmental contaminants. This dissertation examines an important component of the indoor radon problem: the impacts of wind on soil-gas and radon transport and entry into buildings. The research includes experimental and modeling studies of wind`s interactions with a building`s superstructure and the resulting soil-gas and radon flows in the surrounding soil. In addition to exploring the effects of steady winds, a novel modeling technique is developed to examine the impacts of fluctuating winds on soil-gas and radon transport.

  16. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Sourav, E-mail: sourav.bhattacharjee@wur.nl [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Opstal, Edward J. van; Alink, Gerrit M. [Wageningen University, Division of Toxicology (Netherlands); Marcelis, Antonius T. M.; Zuilhof, Han [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands)

    2013-06-15

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size {approx}45 nm) and polystyrene nanoparticles (PSNPs/size {approx}50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  17. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yuki, E-mail: ynagao@jaist.ac.jp; Kubo, Takahiro

    2014-12-30

    Graphical abstract: - Highlights: • Proton transport of fully protonated poly(aspartic acid) thin film was investigated. • The thin film structure differed greatly from the partially protonated one. • Proton transport occurs on the surface, not inside of the thin film. • This result contributes to biological transport systems such as bacteriorhodopsin. - Abstract: Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120–670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  18. Ricci Curvature on Polyhedral Surfaces via Optimal Transportation

    Directory of Open Access Journals (Sweden)

    Benoît Loisel

    2014-03-01

    Full Text Available The problem of correctly defining geometric objects, such as the curvature, is a hard one in discrete geometry. In 2009, Ollivier defined a notion of curvature applicable to a wide category of measured metric spaces, in particular to graphs. He named it coarse Ricci curvature because it coincides, up to some given factor, with the classical Ricci curvature, when the space is a smooth manifold. Lin, Lu and Yau and Jost and Liu have used and extended this notion for graphs, giving estimates for the curvature and, hence, the diameter, in terms of the combinatorics. In this paper, we describe a method for computing the coarse Ricci curvature and give sharper results, in the specific, but crucial case of polyhedral surfaces.

  19. Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

    Directory of Open Access Journals (Sweden)

    K. Yi

    2017-07-01

    Full Text Available The response of surface ozone (O3 concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM. Idealized, spatially uniform sea surface temperature (SST anomalies of ±1 °C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1 °C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5 ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage

  20. Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

    Science.gov (United States)

    Yi, Kan; Liu, Junfeng; Ban-Weiss, George; Zhang, Jiachen; Tao, Wei; Cheng, Yanli; Tao, Shu

    2017-07-01

    The response of surface ozone (O3) concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM). Idealized, spatially uniform sea surface temperature (SST) anomalies of ±1 °C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1 °C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5 ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR) analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage between basin-scale SST

  1. A New Concept to Transport a Droplet on Horizontal Hydrophilic/Hydrophobic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook [Kookmin Univ., Seoul (Korea, Republic of)

    2014-03-15

    A fluid transport technique is a key issue for the development of microfluidic systems. In this paper, a new concept for transporting a droplet without external power sources is proposed and verified numerically. The proposed device is a heterogeneous surface which has both hydrophilic and hydrophobic horizontal surfaces. The numerical simulation to demonstrate the new concept is conducted by an in-house solution code (PowerCFD) which employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method (CICSAM) in a volume of fluid (VOF) scheme for phase interface capturing. It is found that the proposed concept for droplet transport shows superior performance for droplet transport in microfluidic systems.

  2. Effects of trans-Eurasian transport of air pollutants on surface ozone concentrations over Western China

    Science.gov (United States)

    Li, Xiaoyuan; Liu, Junfeng; Mauzerall, Denise L.; Emmons, Louisa K.; Walters, Stacy; Horowitz, Larry W.; Tao, Shu

    2014-11-01

    Due to a lack of industrialization in Western China, surface air there was, until recently, believed to be relatively unpolluted. However, recent measurements and modeling studies have found high levels of ozone (O3) there. Based on the state-of-the-science global chemical transport model MOZART-4, we identify the origin, pathway, and mechanism of trans-Eurasian transport of air pollutants to Western China in 2000. MOZART-4 generally simulates well the observed surface O3 over inland areas of China. Simulations find surface ozone concentrations over Western China on average to be about 10 ppbv higher than Eastern China. Using sensitivity studies, we find that anthropogenic emissions from all Eurasian regions except China contribute 10-15 ppbv surface O3 over Western China, superimposed upon a 35-40 ppbv natural background. Transport from European anthropogenic sources to Northwestern China results in 2-6 ppbv O3 enhancements in spring and summer. Indian anthropogenic sources strongly influence O3 over the Tibetan Plateau during the summer monsoon. Transport of O3 originating from emissions in the Middle East occasionally reach Western China and increase surface ozone there by about 1-4 ppbv. These influences are of similar magnitude as trans-Pacific and transatlantic transport of O3 and its precursors, indicating the significance of trans-Eurasian ozone transport in hemispheric transport of air pollution. Our study further indicates that mitigation of anthropogenic emissions from Europe, the Indian subcontinent, and the Middle East could benefit public health and agricultural productivity in Western China.

  3. Effects of trans-Eurasian transport of anthropogenic pollutants on surface ozone concentrations over China

    Science.gov (United States)

    Liu, J.; Li, X.; Mauzerall, D. L.; Emmons, L. K.; Horowitz, L. W.; Guo, Y.; Tao, S.

    2015-12-01

    Due to a lack of industrialization in Western China, surface air there was, until recently, believed to be relatively unpolluted. However, recent measurements and modeling studies have found high levels of ozone (O3) there. Based on the state-of-the-science global chemical transport model MOZART-4, we identify the origin, pathway, and mechanism of trans-Eurasian transport of air pollutants to Western China in 2000. MOZART-4 generally simulates well the observed surface O3 over inland areas of China. Simulations find surface ozone concentrations over Western China on average to be about 10 ppbv higher than Eastern China. Using sensitivity studies as well as a fully-tagged approach, we find that anthropogenic emissions from all Eurasian regions except China contribute 10-15 ppbv surface O3 over Western China, superimposed upon a 35-40 ppbv natural background. Transport from European anthropogenic sources to Northwestern China results in 2-6 ppbv O3 enhancements in spring and summer. Indian anthropogenic sources strongly influence O3 over the Tibetan Plateau during the summer monsoon. Transport of O3 originating from emissions in the Middle East occasionally reach Western China and increase surface ozone there by about 1-4 ppbv. These influences are of similar magnitude as trans-Pacific and transatlantic transport of O3 and its precursors, indicating the significance of trans-Eurasian ozone transport in hemispheric transport of air pollution. Our study further indicates that mitigation of anthropogenic emissions from Europe, the Indian subcontinent, and the Middle East could benefit public health and agricultural productivity in Western China.

  4. Light-Driven Transport of a Liquid Marble with and against Surface Flows.

    Science.gov (United States)

    Kavokine, Nikita; Anyfantakis, Manos; Morel, Mathieu; Rudiuk, Sergii; Bickel, Thomas; Baigl, Damien

    2016-09-01

    Liquid marbles, that is, liquid drops coated by a hydrophobic powder, do not wet any solid or liquid substrate, making their transport and manipulation both highly desirable and challenging. Herein, we describe the light-driven transport of floating liquid marbles and emphasize a surprising motion behavior. Liquid marbles are deposited on a water solution containing photosensitive surfactants. Irradiation of the solution generates photoreversible Marangoni flows that transport the liquid marbles toward UV light and away from blue light when the thickness of the liquid substrate is large enough (Marangoni regime). Below a critical thickness, the liquid marbles move in the opposite direction to that of the surface flow at a speed increasing with decreasing liquid thickness (anti-Marangoni). We demonstrate that the anti-Marangoni motion is driven by the free surface deformation, which propels the non-wetting marble against the surface flow. We call this behavior "slide effect".

  5. Surface proton transport of fully protonated poly(aspartic acid) thin films on quartz substrates

    Science.gov (United States)

    Nagao, Yuki; Kubo, Takahiro

    2014-12-01

    Thin film structure and the proton transport property of fully protonated poly(aspartic acid) (P-Asp100) have been investigated. An earlier study assessed partially protonated poly(aspartic acid), highly oriented thin film structure and enhancement of the internal proton transport. In this study of P-Asp100, IR p-polarized multiple-angle incidence resolution (P-MAIR) spectra were measured to investigate the thin film structure. The obtained thin films, with thicknesses of 120-670 nm, had no oriented structure. Relative humidity dependence of the resistance, proton conductivity, and normalized resistance were examined to ascertain the proton transport property of P-Asp100 thin films. The obtained data showed that the proton transport of P-Asp100 thin films might occur on the surface, not inside of the thin film. This phenomenon might be related with the proton transport of the biological system.

  6. Continuous directional water transport on the peristome surface of Nepenthes alata

    Science.gov (United States)

    Chen, Huawei; Zhang, Pengfei; Zhang, Liwen; Liu, Hongliang; Jiang, Ying; Zhang, Deyuan; Han, Zhiwu; Jiang, Lei

    2016-04-01

    Numerous natural systems contain surfaces or threads that enable directional water transport. This behaviour is usually ascribed to hierarchical structural features at the microscale and nanoscale, with gradients in surface energy and gradients in Laplace pressure thought to be the main driving forces. Here we study the prey-trapping pitcher organs of the carnivorous plant Nepenthes alata. We find that continuous, directional water transport occurs on the surface of the ‘peristome’—the rim of the pitcher—because of its multiscale structure, which optimizes and enhances capillary rise in the transport direction, and prevents backflow by pinning in place any water front that is moving in the reverse direction. This results not only in unidirectional flow despite the absence of any surface-energy gradient, but also in a transport speed that is much higher than previously thought. We anticipate that the basic ‘design’ principles underlying this behaviour could be used to develop artificial fluid-transport systems with practical applications.

  7. Tunable Surface Hydrophobicity and Fluid Transport through Nanoporous Membranes

    Science.gov (United States)

    Ostrowski, Joseph H. J.

    There are more than three billion people across the globe that struggle to obtain clean drinkable water. One of the most promising avenues for generating potable water is through reverse osmosis and nanofiltration. Both solutions require a semipermeable membrane that prohibits passage of unwanted solute particles but allows passage of the solvent. Atomically thin two-dimensional membranes based on porous graphene show great promise as semipermeable materials, but modeling fluid flow on length scales between the microscopic (nanometer and smaller) and macroscopic (micron and larger) regimes presents formidable challenges. This thesis explores both equilibrium and nonequilibrium aspects of this problem and develops new methodology for simulating systems away from thermal equilibrium. First, we hypothesize that there is a wetting penalty for water as it tries to breach a sheet of graphene that should be naturally hydrophobic. By using equilibrium molecular dynamics simulations, we show that the hydrophobicity depends sensitively on the degree of electrical doping, offering an opportunity to tune the hydrophobic effect of graphene using small amounts of doping. The wetting contact angle, a measure of hydrophobicity, changes dramatically with the voltage applied to single layer graphene. We find that the sensitivity of the hydrophobic effect to voltage depends not on hydrogen bonding motifs at the interface between graphene and water, but instead on a phenomenon known as electrowetting. The theory of electrowetting predicts that the difference in surface tensions that defines the contact angle is quartic in the voltage, rather than quadratic, as it would be in bilayer graphene or in a two-dimensional metal. To explore the nonequilibrium aspects of fluid passage through atomically thin membranes, we developed a molecular dynamics methodology for simulating fluid flow at constant flux based on Gauss's principle of least constraint. This method develops microscopic

  8. Corresponding-states principle and its practice thermodynamic, transport and surface properties of fluids

    CERN Document Server

    Xiang, Hong Wei

    2005-01-01

    The corresponding-states principle helps the understanding and calculating of thermodynamic, transport, and surface properties of substances in various states, required by our modern lifestyle. The Corresponding-States Principle and its Practice: Thermodynamic, Transport and Surface Properties of Fluids describes the origins and applications of the principle from a universal point of view with comparisons to experimental data where possible. It uses the universal theory to explain present theories. Emphasis is on the properties of pure systems, and the corresponding-states theory can also be e

  9. Packet radio data link applications in the NASA Langley Research Center Transport Systems Research Vehicle

    Science.gov (United States)

    Easley, Wesley C.; Carter, Donald; Mcluer, David G.

    1994-01-01

    An amateur packet radio system operating in the very high frequency (VHF) range has been implemented in the Transport Systems Research Vehicle at the NASA Langley Research Center to provide an economical, bidirectional, real-time, ground-to-air data link. The packet system has been used to support flight research involving air traffic control (ATC), differential global positioning systems (DGPS), and windshear terminal doppler weather radar (TDWR). A data maximum rate of 2400 baud was used. Operational reliability of the packet system has been very good. Also, its versatility permits numerous specific configurations. These features, plus its low cost, have rendered it very satisfactory for support of data link flight experiments that do not require high data transfer rates.

  10. Fate of Uranium During Transport Across the Groundwater-Surface Water Interface

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, Peter R. [Princeton Univ., NJ (United States); Kaplan, Daniel I. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-30

    Discharge of contaminated groundwater to surface waters is of concern at many DOE facilities. For example, at F-Area and TNX-Area on the Savannah River Site, contaminated groundwater, including uranium, is already discharging into natural wetlands. It is at this interface where contaminants come into contact with the biosphere. These this research addressed a critical knowledge gap focusing on the geochemistry of uranium (or for that matter, any redox-active contaminant) in wetland systems. Understanding the interactions between hydrological, microbial, and chemical processes will make it possible to provide a more accurate conceptual and quantitative understanding of radionuclide fate and transport under these unique conditions. Understanding these processes will permit better long-term management and the necessary technical justification for invoking Monitored Natural Attenuation of contaminated wetland areas. Specifically, this research did provide new insights on how plant-induced alterations to the sediment biogeochemical processes affect the key uranium reducing microorganisms, the uranium reduction, its spatial distribution, the speciation of the immobilized uranium, and its long-term stability. This was achieved by conducting laboratory mesocosm wetland experiments as well as field measurements at the SRNL. Results have shown that uranium can be immobilized in wetland systems. To a degree some of the soluble U(VI) was reduced to insoluble U(IV), but the majority of the immobilized U was incorporated into iron oxyhydroxides that precipitated onto the root surfaces of wetland plants. This U was immobilized mostly as U(VI). Because it was immobilized in its oxidized form, results showed that dry spells, resulting in the lowering of the water table and the exposure of the U to oxic conditions, did not result in U remobilization.

  11. Towards setting a research agenda around mainstreaming gender in the transport sector

    CSIR Research Space (South Africa)

    Mashiri, M

    2005-07-01

    Full Text Available . As Mahapa points out, transport programs have tended to “function in ways which priorities men’s needs and viewpoints over those of women”. As such, transport needs arising from women’s multiple roles are often not adequately addressed in transport research...

  12. Experience of IEA-R1 research reactor spent fuel transportation back to United States

    Energy Technology Data Exchange (ETDEWEB)

    Frajndlich, Roberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Operacao do Reator IEAR-R1m]. E-mail: frajndli@net.ipen.br; Perrotta, Jose A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div.de Engenharia do Nucleo]. E-mail: perrotta@net.ipen.br; Maiorino, Jose Rubens [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Diretoria de Reatores]. E-mail: maiorino@net.ipen.br; Soares, Adalberto Jose [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Dept. de Reatores]. E-mail: ajsoares@net.ipen.br

    1998-07-01

    IPEN/CNEN-SP is sending the IEA-R1 Research Reactor spent fuels from USA origin back to this country. This paper describes the experience in organizing the negotiations, documents and activities to perform the transport. Subjects as cask licensing, transport licensing and fuel failure criteria for transportation are presented. (author)

  13. Scientific research about climate change mitigation in transport: a critical review

    NARCIS (Netherlands)

    Schwanen, T.; Banister, D.; Anable, J.

    2011-01-01

    This paper seeks to develop a deeper understanding of the research on climatechangemitigation in transport. We suggest that work to date has focused on the effects of improvements in transport technologies, changes in the price of transport, physical infrastructure provision, behavioural change and

  14. Scientific research about climate change mitigation in transport: a critical review

    NARCIS (Netherlands)

    Schwanen, T.; Banister, D.; Anable, J.

    2011-01-01

    This paper seeks to develop a deeper understanding of the research on climatechangemitigation in transport. We suggest that work to date has focused on the effects of improvements in transport technologies, changes in the price of transport, physical infrastructure provision, behavioural change and

  15. A simple approach to fabricate the rose petal-like hierarchical surfaces for droplet transportation

    Science.gov (United States)

    Yuan, Chao; Huang, Mengyu; Yu, Xingjian; Ma, Yupu; Luo, Xiaobing

    2016-11-01

    Precise transportation of liquid microdroplets is a great challenge in the microfluidic field. A sticky superhydrophobic surface with a high static contact angle (CA) and a large contact angle hysteresis (CAH) is recognized as the favorable tool to deal with the challenging job. Some approaches have been proposed to fabricate such surface, such as mimicing the dual-scale hierarchical structure of a natural material, like rose petal. However, the available approaches normally require multiple processing steps or are carried out with great expense. In this study, we report a straightforward and inexpensive method for fabricating the sticky superhydrophobic surfaces. The fabrication relies on electroless galvanic deposition to coat the copper substrates with a textured layer of silver. The whole fabrication process is carried out under ambient conditions by using conventional laboratory materials and equipments, and generally take less than 15 min. Despite the simplicity of this fabrication method, the rose petal-like hierarchical structures and the corresponding sticky superhydrophobic wetting properties were well achieved on the artificial surfaces. For instance, the surface with a deposition time of 10 s exhibits the superhydrophobity with a CA of 151.5°, and the effective stickiness with a CAH of 56.5°. The prepared sticky superhydrophobic surfaces are finally shown in the application of droplet transportation, in which the surface acts as a mechanical hand to grasp and transport the water droplet.

  16. IOT technology application model research of transportation industry in China

    Institute of Scientific and Technical Information of China (English)

    Lai Mingyong; Zhou Tang; Liu Zhengchi

    2013-01-01

    The paper studied the connection between intemet of things (IOT) technology and transportation industry.Meanwhile,the definition of IOT in transportation was given.Concerning that many problems occurred during the process of traditional intelligent transportation system,the paper proposed a promising model of IOT in transportation.The advantage of the information utilization model from information to function was confirmed through comparative study.Finally,the model presented that a real interconnection of transportation would be achieved based on the unified information collection.It can greatly save cost on technology transfer,exploit potential value of information,and promote the emergence of a sustainable information service market and the industrial upgrade.

  17. Coupled Soil Water and Heat Transport Near the Land Surface in Arid and Semiarid Regions - Multi-Domain Modeling

    Science.gov (United States)

    Mohanty, Binayak; Yang, Zhenlei

    2016-04-01

    Understanding and simulating coupled water and heat transfer appropriately in the shallow subsurface is of vital significance for accurate prediction of soil evaporation that would improve the coupling between land surface and atmosphere, which consequently could enhance the reliability of weather as well as climate forecast. The theory of Philip and de Vries (1957), accounting for water vapor diffusion only, was considered physically incomplete and consequently extended and improved by several researchers by explicitly taking water vapor convection, dispersion or air flow into account. It is generally believed that the soil moisture is usually low in the near surface layer under highly transient field conditions, particularly in arid and semiarid regions, and that accurate characterization of water vapor transport is critical when modeling simultaneous water and heat transport in the shallow field soils. The first objective of this study is thus mainly to test existing coupled water and heat transport theories and to develop reasonable and simplified numerical models using field experimental data collected under semi-arid and arid hydro-climatic conditions. In addition, more complex multi-domain models are developed for ubiquitous heterogeneous terrestrial surfaces such as horizontal textural contrasts or structured heterogeneity including macropores (fractures, cracks, root channels, etc.). This would make coupled water and heat transfer models applicable in such non-homogeneous soils more meaningful and enhance the skill of land-atmosphere interaction models at a larger context.

  18. Probing the electronic transport on the reconstructed Au/Ge(001 surface

    Directory of Open Access Journals (Sweden)

    Franciszek Krok

    2014-09-01

    Full Text Available By using scanning tunnelling potentiometry we characterized the lateral variation of the electrochemical potential µec on the gold-induced Ge(001-c(8 × 2-Au surface reconstruction while a lateral current flows through the sample. On the reconstruction and across domain boundaries we find that µec shows a constant gradient as a function of the position between the contacts. In addition, nanoscale Au clusters on the surface do not show an electronic coupling to the gold-induced surface reconstruction. In combination with high resolution scanning electron microscopy and transmission electron microscopy, we conclude that an additional transport channel buried about 2 nm underneath the surface represents a major transport channel for electrons.

  19. Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.; Clark, Kyle; Weber, Adam Z.; Kostecki, Robert

    2011-08-01

    The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

  20. Interdisciplinary Research to Elucidate Mechanisms Governing Silver Nanoparticle Fate and Transport in Porous Media

    Science.gov (United States)

    Pennell, K. D.; Mittleman, A.; Taghavy, A.; Fortner, J.; Lantagne, D.; Abriola, L. M.

    2015-12-01

    Interdisciplinary Research to Elucidate Mechanisms Governing Silver Nanoparticle Fate and Transport in Porous Media Anjuliee M. Mittelman, Amir Taghavy, Yonggang Wang, John D. Fortner, Daniele S. Lantagne, Linda M. Abriola and Kurt D. Pennell* Detailed knowledge of the processes governing nanoparticle transport and reactivity in porous media is essential for accurate predictions of environmental fate, water and wastewater treatment system performance, and assessment of potential risks to ecosystems and water supplies. To address these issues, an interdisciplinary research team combined experimental and mathematical modeling studies to investigate the mobility, dissolution, and aging of silver nanoparticles (nAg) in representative aquifer materials and ceramic filters. Results of one-dimensional column studies, conducted with water-saturated sands maintained at pH 4 or 7 and three levels of dissolved oxygen (DO), revealed that fraction of silver mass eluted as Ag+ increased with increasing DO level, and that the dissolution of attached nAg decreased over time as a result of surface oxidation. A hybrid Eulerain-Lagragian nanoparticle transport model, which incorporates DO-dependent dissolution kinetics and particle aging, was able to accurately simulate nAg mobility and Ag+ release measured in the column experiments. Model sensitivity analysis indicated that as the flow velocity and particle size decrease, nAg dissolution and Ag+ transport processes increasingly govern silver mobility. Consistent results were obtained in studies of ceramic water filters treated with nAg, where silver elution was shown to be governed by nAg dissolution to form Ag+ and subsequent cation exchange reactions. Recent studies explored the effects of surface coating aging on nAg aggregation, mobility and dissolution. Following ultraviolet light, nAg retention in water saturated sand increased by 25-50%, while up to 50% of the applied mass eluted as Ag+ compared to less than 1% for un-aged n

  1. Formulation Effects and the Off-target Transport of Pyrethroid Insecticides from Urban Hard Surfaces

    OpenAIRE

    2010-01-01

    Controlled rainfall experiments utilizing drop forming rainfall simulators were conducted to study various factors contributing to off-target transport of off-the-shelf formulated pyrethroid insecticides from concrete surfaces. Factors evaluated included active ingredient, product formulation, time between application and rainfall (set time), and rainfall intensity. As much as 60% and as little as 0.8% of pyrethroid applied could be recovered in surface runoff depending primarily on product f...

  2. Patterned gradient surface for spontaneous droplet transportation and water collection: simulation and experiment

    Science.gov (United States)

    Tan, Xianhua; Zhu, Yiying; Shi, Tielin; Tang, Zirong; Liao, Guanglan

    2016-11-01

    We demonstrate spontaneous droplet transportation and water collection on wedge-shaped gradient surfaces consisting of alternating hydrophilic and hydrophobic regions. Droplets on the surfaces are modeled and simulated to analyze the Gibbs free energy and free energy gradient distributions. Big half-apex angle and great wettability difference result in considerable free energy gradient, corresponding to large driving force for spontaneous droplet transportation, thus causing the droplets to move towards the open end of the wedge-shaped hydrophilic regions, where the Gibbs free energy is low. Gradient surfaces are then fabricated and tested. Filmwise condensation begins on the hydrophilic regions, forming wedge-shaped tracks for water collection. Dropwise condensation occurs on the hydrophobic regions, where the droplet size distribution and departure diameters are controlled by the width of the regions. Condensate water from both the hydrophilic and hydrophobic regions are collected directionally to the open end of the wedge-shaped hydrophilic regions, agreeing with the simulations. Directional droplet transport and controllable departure diameters make the branched gradient surfaces more efficient than smooth surfaces for water collection, which proves that gradient surfaces are potential in water collection, microfluidic devices, anti-fogging and self-cleaning.

  3. A GERMAN EXAMPLE FOR A PUBLIC PRIVATE PARTNERSHIP IN TRANSPORT RESEARCH

    OpenAIRE

    Boltze, Manfred

    2003-01-01

    In 1998, a new partnership for transport research was founded in Germany's central region Frankfurt RheinMain by major transport authorities and operators, involving partners from industry and consultancy, and supported by the Hessen State Government. This ZIV is an institute at Darmstadt University of Technology, and improves the exchange between research and practice. The article provides organisational details of this public private partnership. The ZIV working areas cover Transport Infras...

  4. Professor says research shows slow progress in transportation equity

    OpenAIRE

    Micale, Barbara L.

    2005-01-01

    Tom Sanchez of Dumfries, Va., associate professor of urban affairs and planning in the College of Architecture and Urban Studies at Virginia Tech, National Capital Region, was an invited panelist at a national workshop, "Transportation Equity: Past, Present, and Future," sponsored by the U.S. Department of Transportation at Troy University in Montgomery, Ala., to commemorate the 50th anniversary of the Montgomery Bus Boycott.

  5. Cities and transport networks in shipping and logistics research

    OpenAIRE

    Ducruet, César; Lugo, Igor

    2013-01-01

    International audience; While shipping and logistics studies often describe the flows and networks on the level of firms and terminals rather than cities, urban studies pay limited attention to transport infrastructure and material flows. The renewal of network analysis based on complex systems will be discussed in this paper as a potential bridge between those two approaches. It particularly focuses on how transport and urban elements can be mutually integrated. The main conclusion points at...

  6. Mass Transport in a Thin Layer of Bi-Viscous Mud Under Surface Waves

    Institute of Scientific and Technical Information of China (English)

    NG Chiu-on; FU Sau-chung; BAI Yu-chuan(白玉川)

    2002-01-01

    The mass transport in a thin layer of non-Newtonian bed mud under surface waves is examined with a two-fluidStokes boundary layer model. The mud is assumed to be a bi-viscous fluid, which tends to resist motion for small-appliedstresses, but flows readily when the yield stress is exceeded. Asymptotic expansions suitable for shallow fluid layers areapplied, and the second-order solutions for the mass transport induced by surface progressive waves are obtained numeri-cally. It is found that the stronger the non-Newtonian behavior of the mud, the more pronounced intermittency of theflow. Consequently, the mass transport velocity is diminished in magnitude, and can even become negative (i. e., oppo-site to wave propagation) for a certain range of yield stress.

  7. Ambipolar surface state transport in nonmetallic stoichiometric Bi2Se3 crystals

    Science.gov (United States)

    Syers, Paul; Paglione, Johnpierre

    2017-01-01

    Achieving true bulk insulating behavior in Bi2Se3 , the archetypal topological insulator with a simplistic one-band electronic structure and sizable band gap, has been prohibited by a well-known self-doping effect caused by selenium vacancies, whose extra electrons shift the chemical potential into the bulk conduction band. We report a synthesis method for achieving stoichiometric Bi2Se3 crystals that exhibit nonmetallic behavior in electrical transport down to low temperatures. Hall-effect measurements indicate the presence of both electron- and holelike carriers, with the latter identified with surface state conduction and the achievement of ambipolar transport in bulk Bi2Se3 crystals without gating techniques. With carrier mobilities surpassing the highest values yet reported for topological surface states in this material, the achievement of ambipolar transport via upward band bending is found to provide a key method to advancing the potential of this material for future study and applications.

  8. Mass transport in a thin layer of power-law mud under surface waves

    Science.gov (United States)

    Liu, Jie; Bai, Yuchuan; Xu, Dong

    2017-02-01

    The mass transport velocity in a two-layer system is studied theoretically. The wave motion is driven by a periodic pressure load on the free water surface, and mud in the lower layer is described by a power-law rheological model. Perturbation analysis is performed to the second order to find the mean Eulerian velocity. A numerical iteration method is employed to solve the non-linear governing equation at the leading order. The influence of rheological properties on fluid motion characteristics including the flow field, the surface displacement, the mass transport velocity, and the net discharge rates are investigated based on theoretical results. Theoretical analysis shows that under the action of interfacial shearing, a recirculation structure may appear near the interface in the upper water layer. A higher mass transport velocity at the interface does not necessarily mean a higher discharge rate for a pseudo-plastic fluid mud.

  9. Nonadiabaticity and single-electron transport driven by surface acoustic waves

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Niu, Q.; Pustilnik, M.

    1999-01-01

    Single-electron transport driven by surface acoustic waves (SAW) through a narrow constriction, formed in a two-dimensional electron gas, is studied theoretically. Due to long-range Coulomb interaction, the tunneling coupling between the electron gas and the moving minimum of the SAW...

  10. Quantum transport and two-parameter scaling at the surface of a weak topological insulator.

    Science.gov (United States)

    Mong, Roger S K; Bardarson, Jens H; Moore, Joel E

    2012-02-17

    Weak topological insulators have an even number of Dirac cones in their surface spectrum and are thought to be unstable to disorder, which leads to an insulating surface. Here we argue that the presence of disorder alone will not localize the surface states; rather, the presence of a time-reversal symmetric mass term is required for localization. Through numerical simulations, we show that in the absence of the mass term the surface always flow to a stable metallic phase and the conductivity obeys a one-parameter scaling relation, just as in the case of a strong topological insulator surface. With the inclusion of the mass, the transport properties of the surface of a weak topological insulator follow a two-parameter scaling form.

  11. Solute transport predicts scaling of surface reaction rates in porous media: Applications to silicate weathering

    CERN Document Server

    Hunt, Allen G; Ghanbarian, Behzad

    2013-01-01

    We apply our theory of conservative solute transport, based on concepts from percolation theory, directly and without modification to reactive solute transport. This theory has previously been shown to predict the observed range of dispersivity values for conservative solute transport over ten orders of magnitude of length scale. We now show that the temporal dependence derived for the solute velocity accurately predicts the time-dependence for the weathering of silicate minerals over nine orders of magnitude of time scale, while its predicted length dependence agrees with data obtained for reaction rates over five orders of magnitude of length scale. In both cases, it is possible to unify lab and field results. Thus, net reaction rates appear to be limited by solute transport velocities. We suggest the possible relevance of our results to landscape evolution of the earth's terrestrial surface.

  12. Reliable transport through a microfabricated X-junction surface-electrode ion trap

    Science.gov (United States)

    Wright, Kenneth; Amini, Jason M.; Faircloth, Daniel L.; Volin, Curtis; Doret, S. Charles; Hayden, Harley; Pai, C.-S.; Landgren, David W.; Denison, Douglas; Killian, Tyler; Slusher, Richart E.; Harter, Alexa W.

    2013-03-01

    We report the design, fabrication and characterization of a microfabricated surface-electrode ion trap that supports controlled transport through the two-dimensional intersection of linear trapping zones arranged in a 90° cross. The trap is fabricated with very large scalable integration techniques which are compatible with scaling to a large quantum information processor. The shape of the radio-frequency electrodes is optimized with a genetic algorithm to reduce axial pseudopotential barriers and minimize ion heating during transport. Seventy-eight independent dc control electrodes enable fine control of the trapping potentials. We demonstrate reliable ion transport between junction legs and determine the rate of ion loss due to transport. Doppler-cooled ions survive more than 105 round-trip transits between junction legs without loss and more than 65 consecutive round trips without laser cooling.

  13. Heating and ion transport in a Y-junction surface-electrode trap

    CERN Document Server

    Shu, G; Volin, C; Buikema, A; Nichols, C S; Stick, D; Brown, Kenneth R

    2014-01-01

    We measure ion heating following transport throughout a Y-junction surface-electrode ion trap. By carefully selecting the trap voltage update rate during adiabatic transport along a trap arm, we observe minimal heating relative to the anomalous heating background. Transport through the junction results in an induced heating between 37 and 150 quanta in the axial direction per traverse. To reliably measure heating in this range, we compare the experimental sideband envelope, including up to fourth-order sidebands, to a theoretical model. The sideband envelope method allows us to cover the intermediate heating range inaccessible to the first-order sideband and Doppler recooling methods. We conclude that quantum information processing in this ion trap will likely require sympathetic cooling in order to support high fidelity gates after junction transport.

  14. Physical and logistical considerations of using ultrasonic anemometers in aeolian sediment transport research

    Science.gov (United States)

    Walker, Ian J.

    2005-05-01

    Recently, ultrasonic anemometers (UAs) have become available for precise, high-frequency measurement of three-dimensional velocity and turbulence properties. Except for a few wind tunnel and computational fluid dynamics (CFD) simulations, advances in aeolian sediment transport and bedform research have been limited to field studies using instrumentation that is either incapable of measuring turbulence (e.g., cup anemometers) or unable to withstand sediment-laden airflow (e.g., hotfilms). In contrast, extensive progress has occurred in fluvial research where turbulence instrumentation has been available for some time. This paper provides a pragmatic discussion on using UAs in aeolian research. Recent advances using this technology are reviewed and key physical and logistical considerations for measuring airflow properties and near-surface shear stress using UAs over complex terrain are discussed. Physical considerations include limitations of applying boundary layer theory to flow over natural surfaces such as non-logarithmic velocity profiles resulting from roughness- and topographically induced effects and the inability of instrumentation to measure within the thin constant-stress region. These constraints hinder accurate shear velocity ( u*), shear stress and sand transport estimation. UAs allow measurement of turbulent Reynolds stress (RS) that, in theory, should equal profile-derived shear stress. Discrepancies often exist between these quantities however due to three-dimensional (spanwise) flow components and rapid distortion effects (i.e., unbalanced production and dissipation of turbulence) common in flow over complex terrain. While the RS approach yields information on turbulent contributions to near-surface stress generation, little evidence exists showing that RS is a better measure of forces responsible for sediment transport. Consequently, predictive equations for sediment transport using RS do not exist. There is also a need to identify the role of

  15. Microfour-point probe for studying electronic transport through surface states

    DEFF Research Database (Denmark)

    Petersen, Christian Leth; Grey, Francois; Shiraki, I.

    2000-01-01

    Microfour-point probes integrated on silicon chips have been fabricated with probe spacings in the range 4-60 mum. They provide a simple robust device for electrical transport measurements at surfaces, bridging the gap between conventional macroscopic four-point probes and scanning tunneling...... microscopy. Measurements on Si(111) surfaces in ultrahigh vacuum reveal that the Si(111)-root 3x root3-Ag structure induced by a monolayer of Ag atoms has a four-point resistance two orders of magnitude lower than that of the Si(111)-7x7 clean surface. We attribute this remarkable difference to direct...

  16. Quantum transport in the surface states of epitaxial Bi(111) thin films

    Science.gov (United States)

    Zhu, Kai; Wu, Lin; Gong, Xinxin; Xiao, Shunhao; Jin, Xiaofeng

    2016-09-01

    Although bulk Bi is a prototypical semimetal with a topologically trivial electronic band structure, we show by various quantum transport measurements that epitaxial Bi(111) thin films have unexpected and nontrivial properties. Not only the top and the bottom but also the side surfaces of epitaxial Bi(111) thin films are always robustly metallic while the interior has already become insulating. We identify the coupling between the top and the bottom surface states that drives the two originally independent surface conducting channels into a single connected one. The properties of Bi(111) thin films realized could lead to promising applications in spintronics.

  17. Sea Surface Sound: discussion session on future research and applications

    Science.gov (United States)

    Buckingham, M. J.; Potter, J. R.

    On one evening during the week of the workshop, a brain-storming session was held with a view to identifying important areas of research into sea surface sound that should be addressed in the future. Potential applications of sea surface sound were included in the discussion. Acting as chairman, Michael Buckingham (MB) introduced the session, which was attended by most of the participants at the workshop. The intention was to encourage the participants to explore, in an informal setting, the future of sea surface sound. A summary of comments and conclusions, compiled from MB's notes of the discussion, is presented below…

  18. Transport of particles by surface waves: a modification of the classical bouncer model

    Energy Technology Data Exchange (ETDEWEB)

    Ragulskis, M [Department of Mathematical Research in Systems, Kaunas University of Technology, Studentu 50-222, 51638 Kaunas (Lithuania); Sanjuan, M A F [Nonlinear Dynamics and Chaos Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)], E-mail: minvydas.ragulskis@ktu.lt, E-mail: miguel.sanjuan@urjc.es

    2008-08-15

    We consider a ball under the influence of gravity on a platform. A propagating surface wave travels on the surface of the platform, while the platform remains motionless. This is a modification of the classical bouncing ball problem and describes the transport of particles by surface waves. Phase and velocity maps cannot be expressed in an explicit form owing to implicit formulations, and no formal analytical analysis is possible. Numerical analysis shows that the transition to chaos is produced via a period doubling route, which is a common property for classical bouncers. The bouncing process can be sensitive to the initial conditions, which can build the ground for control techniques that can dramatically increase the effectiveness of particle transport in practical applications.

  19. The Effect of Surface Roughness on Fluid Configuration and Solute Transport in Unsaturated Porous Media

    Science.gov (United States)

    Kibbey, T. C.

    2013-12-01

    When describing the configuration of water in unsaturated media, a distinction is often made between water that is held by capillary forces between grains (capillary water), and water associated with adsorbed films on solid surfaces (film water). The objective of this work was to better understand the nature of the water associated with solid surfaces, with emphasis on understanding the configuration of water on rough natural surfaces. Stereoscopic SEM was used to determine elevation maps on a range of different natural solid surfaces. A computational technique was then developed to calculate the configuration of water on the surfaces as a function of capillary pressure. Calculations of fluid configurations show that, except at extremely high capillary pressures, fluid configuration is dominated by bridging of surface roughness features, even for extremely smooth surfaces. Results suggest that true adsorbed films are likely extremely rare in the environment except under near-dry, ultra-high capillary pressure conditions. This result has significant implications for understanding fate and transport within the unsaturated zone. Preliminary simulations exploring the impact on transport will be discussed.

  20. Surface Effect on Oil Transportation in Nanochannel: a Molecular Dynamics Study.

    Science.gov (United States)

    Zheng, Haixia; Du, Yonggang; Xue, Qingzhong; Zhu, Lei; Li, Xiaofang; Lu, Shuangfang; Jin, Yakang

    2017-12-01

    In this work, we investigate the dynamics mechanism of oil transportation in nanochannel using molecular dynamics simulations. It is demonstrated that the interaction between oil molecules and nanochannel has a great effect on the transportation properties of oil in nanochannel. Because of different interactions between oil molecules and channel, the center of mass (COM) displacement of oil in a 6-nm channel is over 30 times larger than that in a 2-nm channel, and the diffusion coefficient of oil molecules at the center of a 6-nm channel is almost two times more than that near the channel surface. Besides, it is found that polarity of oil molecules has the effect on impeding oil transportation, because the electrostatic interaction between polar oil molecules and channel is far larger than that between nonpolar oil molecules and channel. In addition, channel component is found to play an important role in oil transportation in nanochannel, for example, the COM displacement of oil in gold channel is very few due to great interaction between oil and gold substrate. It is also found that nano-sized roughness of channel surface greatly influences the speed and flow pattern of oil. Our findings would contribute to revealing the mechanism of oil transportation in nanochannels and therefore are very important for design of oil extraction in nanochannels.

  1. Electronic transport at semiconductor surfaces - from point-contact transistor to micro-four-point probes

    DEFF Research Database (Denmark)

    Hasegawa, S.; Grey, Francois

    2002-01-01

    show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered......The electrical properties of semiconductor surfaces have played a decisive role in one of the most important discoveries of the last century, transistors. In the 1940s, the concept of surface states-new electron energy levels characteristic of the surface atoms-was instrumental in the fabrication...... of the first point-contact transistors, and led to the successful fabrication of field-effect transistors. However, to this day, one property of semiconductor surface states remains poorly understood, both theoretically and experimentally. That is the conduction of electrons or holes directly through...

  2. A GERMAN EXAMPLE FOR A PUBLIC PRIVATE PARTNERSHIP IN TRANSPORT RESEARCH

    Directory of Open Access Journals (Sweden)

    Manfred BOLTZE

    2003-01-01

    Full Text Available In 1998, a new partnership for transport research was founded in Germany's central region Frankfurt RheinMain by major transport authorities and operators, involving partners from industry and consultancy, and supported by the Hessen State Government. This ZIV is an institute at Darmstadt University of Technology, and improves the exchange between research and practice. The article provides organisational details of this public private partnership. The ZIV working areas cover Transport Infrastructure and Traffic Management, Traffic Engineering and Traffic Control, Public Transport, Organisational Concepts for Traffic Management and Mobility Services, Railway Systems and Railway Engineering, and Navigation and Positioning Systems. For each of these areas, basic intentions in research and some project examples are presented. This may also allow some view on the current status of transport research in Germany.

  3. Magnetically Controlled Electronic Transport Properties of a Ferromagnetic Junction on the Surface of a Topological Insulator

    Science.gov (United States)

    Liu, Zheng-Qin; Wang, Rui-Qiang; Deng, Ming-Xun; Hu, Liang-Bin

    2015-06-01

    We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topological insulator. The current-voltage characteristic curve and the tunneling conductance are calculated theoretically. Two interesting transport features are predicted: observable negative differential conductances and linear conductances tunable from unit to nearly zero. These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization. Our results may contribute to the development of high-speed switching and functional applications or electrically controlled magnetization switching. Supported by National Natural Science Foundation of China under Grant Nos. 11174088, 11175067, 11274124

  4. Measurements of wind friction speeds over lava surfaces and assessment of sediment transport

    Science.gov (United States)

    Greeley, Ronald; Iversen, James D.

    1987-01-01

    Wind velocity profiles were obtained over alluvial plains, lava flows, and a cinder cone in the Mojave Desert to determine the wind shear and the potential for particle transport. It was found that aerodynamic roughness for winds increases nearly a factor of 5 as flow crosses from the alluvium to the lava surface, resulting in wind shear that is 21 percent greater. Thus, wind erosion and sand flux may be substantially enhanced over the lava field. Moreover, wind flow turbulence is enhanced in the wake of the cinder cone, which also increases erosion and sediment transportation by the wind.

  5. A controlled field pilot for testing near surface CO2 detection techniques and transport models

    Science.gov (United States)

    Spangler, L.H.; Dobeck, L.M.; Repasky, K.; Nehrir, A.; Humphries, S.; Keith, C.; Shaw, J.; Rouse, J.; Cunningham, A.; Benson, S.; Oldenburg, C.M.; Lewicki, J.L.; Wells, A.; Diehl, R.; Strazisar, B.; Fessenden, J.; Rahn, Thomas; Amonette, J.; Barr, J.; Pickles, W.; Jacobson, J.; Silver, E.; Male, E.; Rauch, H.; Gullickson, K.; Trautz, R.; Kharaka, Y.; Birkholzer, J.; Wielopolski, L.

    2009-01-01

    A field facility has been developed to allow controlled studies of near surface CO2 transport and detection technologies. The key component of the facility is a shallow, slotted horizontal well divided into six zones. The scale and fluxes were designed to address large scale CO2 storage projects and desired retention rates for those projects. A wide variety of detection techniques were deployed by collaborators from 6 national labs, 2 universities, EPRI, and the USGS. Additionally, modeling of CO2 transport and concentrations in the saturated soil and in the vadose zone was conducted. An overview of these results will be presented. ?? 2009 Elsevier Ltd. All rights reserved.

  6. Challenges and future research needs towards international freight transport modelling

    NARCIS (Netherlands)

    Meersman, H.; Ehrler, C.C.; Bruckmann, D.; Chen, T.M.; Francke, J.; Hill, P.; Jackson, C.; Klauenberg, J.; Kurowski, M.; Seidel, S.; Vierth, I.

    2016-01-01

    The advanced internationalisation of markets and production processes continuously adds to the complexity of supply chains. At the same time improving the sustainability of the related international freight transport processes and optimising their efficiency is becoming a topic of central relevance.

  7. The Kuroshio Transport East of Taiwan and the Sea Surface Height Anomaly from the Interior Ocean

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; LIU Qinyu; JIA Yinglai

    2004-01-01

    The relationship between the Kuroshio transport to the east of Taiwan and the SSHA(Sea Surface Height Anomaly)field is studied based on the World Ocean Circulation Experiment(WOCE)PCM-1 moored current meter array observation, the satellite altimeter data from the MSLA(Map of Sea Level Anomaly)products merged with the ERS and TOPEX/POSEIDON(T/P)data sets, and the WOCE satellite-tracked drifting buoy data. It is confirmed that the Kuroshio transport across PCM-1 array highly correlates with the SSHA upstream(22°-24°, 121.75°-124°E). The SSHA is not locally generated by the developed Kuroshio meandering but is from the interior ocean and is propagating westward or northwestward. During the period from October 1992 to January 1998, two events of the northwestward propagating negative SSHA occurred, during which the SSHA merged into the Kuroshio and caused the remarkable low transport events in contrast to the normal westward propagating negative SSHA. It is also shown that the lower Kuroshio transport event would be generated in different ways. The negative anomaly in the upstream of PCM-1 array can reduce the Kuroshio transport by either offshore or onshore Kuroshio meandering. The positive anomaly, which is strong enough to detour the Kuroshio, can cause an offshore meandering and a low transport event at the PCM-1 array.

  8. Predicting uncertainty in sediment transport and landscape evolution - the influence of initial surface conditions

    Science.gov (United States)

    Hancock, G. R.; Coulthard, T. J.; Lowry, J. B. C.

    2016-05-01

    Numerical landscape evolution models were initially developed to examine natural catchment hydrology and geomorphology and have become a common tool to examine geomorphic behaviour over a range of time and space scales. These models all use a digital elevation model (DEM) as a representation of the landscape surface and a significant issue is the quality and resolution of this surface. Here we focus on how subtle perturbations or roughness on the DEM surface can produce alternative model results. This study is carried out by randomly varying the elevations of the DEM surface and examining the effect on sediment transport rates and geomorphology for a proposed rehabilitation design for a post-mining landscape using multiple landscape realisations with increasing magnitudes of random changes. We show that an increasing magnitude of random surface variability does not appear to have any significant effect on sediment transport over millennial time scales. However, the random surface variability greatly changes the temporal pattern or delivery of sediment output. A significant finding is that all simulations at the end of the 10,000 year modelled period are geomorphologically similar and present a geomorphological equifinality. However, the individual patterns of erosion and deposition were different for repeat simulations with a different sequence of random perturbations. The alternative positions of random perturbations strongly influence local patterns of hillslope erosion and evolution together with the pattern and behaviour of deposition. The findings demonstrate the complex feedbacks that occur even within a simple modelled system.

  9. Enhanced Hydrogen Transport over Palladium Ultrathin Films through Surface Nanostructure Engineering.

    Science.gov (United States)

    Abate, Salvatore; Giorgianni, Gianfranco; Gentiluomo, Serena; Centi, Gabriele; Perathoner, Siglinda

    2015-11-01

    Palladium ultrathin films (around 2 μm) with different surface nanostructures are characterized by TEM, SEM, AFM, and temperature programmed reduction (TPR), and evaluated in terms of H2 permeability and H2-N2 separation. A change in the characteristics of Pd seeds by controlled oxidation-reduction treatments produces films with the same thickness, but different surface and bulk nanostructure. In particular, the films have finer and more homogeneous Pd grains, which results in lower surface roughness. Although all samples show high permeo-selectivity to H2 , the samples with finer grains exhibit enhanced permeance and lower activation energy for H2 transport. The analysis of the data suggests that grain boundaries between the Pd grains at the surface favor H2 transfer from surface to subsurface. Thus, the surface nanostructure plays a relevant role in enhancing the transport of H2 over the Pd ultrathin film, which is an important aspect to develop improved membranes that function at low temperatures and toward new integrated process architectures in H2 and syngas production with enhanced sustainability.

  10. Thermally driven transverse transports and magnetic dynamics on a topological surface capped with a ferromagnet strip

    Science.gov (United States)

    Deng, Ming-Xun; Zhong, Ming; Zheng, Shi-Han; Qiu, Jian-Ming; Yang, Mou; Wang, Rui-Qiang

    2016-02-01

    We theoretically study thermally driven transport of the Dirac fermions on the surface of a topological insulator capped with a ferromagnet strip. The generation and manipulation of anomalous Hall and Nernst effects are analyzed, in which the in-plane magnetization of the ferromagnet film is found to take a decisive role. This scenario is distinct from that modulated by Berry phase where the in-plane magnetization is independent. We further discuss the thermal spin-transfer torque as a backaction of the thermoelectric transports on the magnetization and calculate the dynamics of the anomalous Hall and Nernst effects self-consistently. It is found that the magnitude of the long-time steady Hall and Nernst conductance is determined by competition between the magnetic anisotropy and current-induced effective anisotropy. These results open up a possibility of magnetically controlling the transverse thermoelectric transports or thermally manipulating the magnet switching.

  11. Reliable transport through a microfabricated X-junction surface-electrode ion trap

    CERN Document Server

    Wright, Kenneth; Faircloth, Daniel L; Volin, Curtis; Doret, S Charles; Hayden, Harley; Pai, C-S; Landgren, David W; Denison, Douglas; Killian, Tyler; Slusher, Richart E; Harter, Alexa W

    2012-01-01

    We report the design, fabrication, and characterization of a microfabricated surface-electrode ion trap that supports controlled transport through the two-dimensional intersection of linear trapping zones arranged in a ninety-degree cross. The trap is fabricated with very-large-scalable-integration (VLSI) techniques which are compatible with scaling to a larger quantum information processor. The shape of the radio-frequency (RF) electrodes is optimized with a genetic algorithm to minimize axial pseudopotential barriers and to minimize ion heating during transport. Seventy-eight independent DC control electrodes enable fine control of the trapping potentials. We demonstrate reliable ion transport between junction legs, trapping of ion chains with nearly-equal spacing in one of the trap's linear sections, and merging and splitting ions from these chains. Doppler-cooled ions survive more than 10^5 round-trip transits between junction legs without loss and more than sixty-five consecutive round trips without lase...

  12. Transport mechanism of reverse surface leakage current in AlGaN/GaN high-electron mobility transistor with SiN passivation

    Institute of Scientific and Technical Information of China (English)

    郑雪峰; 张进成; 郝跃; 范爽; 陈永和; 康迪; 张建坤; 王冲; 默江辉; 李亮; 马晓华

    2015-01-01

    The transport mechanism of reverse surface leakage current in AlGaN/GaN high-electron mobility transistor (HEMT) becomes one of the most important reliability issues with the downscaling of feature size. In this paper, the research results show that the reverse surface leakage current in AlGaN/GaN HEMT with SiN passivation increases with the enhancement of temperature in a range from 298 K to 423 K. Three possible transport mechanisms are proposed and examined to explain the generation of reverse surface leakage current. By comparing the experimental data with the numerical transport models, it is found that neither Fowler–Nordheim tunneling nor Frenkel–Poole emission can describe the transport of reverse surface leakage current. However, good agreement is found between the experimental data and the two-dimensional variable range hopping (2D-VRH) model. Therefore, it is concluded that the reverse surface leakage current is dominated by the electron hopping through the surface states at barrier layer. Moreover, the activation energy of surface leakage current is extracted, which is around 0.083 eV. Finally, the SiN passivated HEMT with high Al composition and thin AlGaN barrier layer is also studied. It is observed that 2D-VRH still dominates the reverse surface leakage current and the activation energy is around 0.10 eV, which demonstrates that the alteration of AlGaN barrier layer does not affect the transport mechanism of reverse surface leakage current in this paper.

  13. Photoluminescence Imaging of Polyfluorene Surface Structures on Semiconducting Carbon Nanotubes: Implications for Thin Film Exciton Transport.

    Science.gov (United States)

    Hartmann, Nicolai F; Pramanik, Rajib; Dowgiallo, Anne-Marie; Ihly, Rachelle; Blackburn, Jeffrey L; Doorn, Stephen K

    2016-12-27

    Single-walled carbon nanotubes (SWCNTs) have potential to act as light-harvesting elements in thin film photovoltaic devices, but performance is in part limited by the efficiency of exciton diffusion processes within the films. Factors contributing to exciton transport can include film morphology encompassing nanotube orientation, connectivity, and interaction geometry. Such factors are often defined by nanotube surface structures that are not yet well understood. Here, we present the results of a combined pump-probe and photoluminescence imaging study of polyfluorene (PFO)-wrapped (6,5) and (7,5) SWCNTs that provide additional insight into the role played by polymer structures in defining exciton transport. Pump-probe measurements suggest exciton transport occurs over larger length scales in films composed of PFO-wrapped (7,5) SWCNTs, compared to those prepared from PFO-bpy-wrapped (6,5) SWCNTs. To explore the role the difference in polymer structure may play as a possible origin of differing transport behaviors, we performed a photoluminescence imaging study of individual polymer-wrapped (6,5) and (7,5) SWCNTs. The PFO-bpy-wrapped (6,5) SWCNTs showed more uniform intensity distributions along their lengths, in contrast to the PFO-wrapped (7,5) SWCNTs, which showed irregular, discontinuous intensity distributions. These differences likely originate from differences in surface coverage and suggest the PFO wrapping on (7,5) nanotubes produces a more open surface structure than is available with the PFO-bpy wrapping of (6,5) nanotubes. The open structure likely leads to improved intertube coupling that enhances exciton transport within the (7,5) films, consistent with the results of our pump-probe measurements.

  14. Photoluminescence Imaging of Polyfluorene Surface Structures on Semiconducting Carbon Nanotubes: Implications for Thin Film Exciton Transport

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, Nicolai F.; Pramanik, Rajib; Dowgiallo, Anne-Marie; Ihly, Rachelle; Blackburn, Jeffrey L.; Doorn, Stephen K.

    2016-12-27

    Single-walled carbon nanotubes (SWCNTs) have potential to act as light-harvesting elements in thin film photovoltaic devices, but performance is in part limited by the efficiency of exciton diffusion processes within the films. Factors contributing to exciton transport can include film morphology encompassing nanotube orientation, connectivity, and interaction geometry. Such factors are often defined by nanotube surface structures that are not yet well understood. Here, we present the results of a combined pump-probe and photoluminescence imaging study of polyfluorene (PFO)-wrapped (6,5) and (7,5) SWCNTs that provide additional insight into the role played by polymer structures in defining exciton transport. Pump-probe measurements suggest exciton transport occurs over larger length scales in films composed of PFO-wrapped (7,5) SWCNTs, compared to those prepared from PFO-bpy-wrapped (6,5) SWCNTs. To explore the role the difference in polymer structure may play as a possible origin of differing transport behaviors, we performed a photoluminescence imaging study of individual polymer-wrapped (6,5) and (7,5) SWCNTs. The PFO-bpy-wrapped (6,5) SWCNTs showed more uniform intensity distributions along their lengths, in contrast to the PFO-wrapped (7,5) SWCNTs, which showed irregular, discontinuous intensity distributions. These differences likely originate from differences in surface coverage and suggest the PFO wrapping on (7,5) nanotubes produces a more open surface structure than is available with the PFO-bpy wrapping of (6,5) nanotubes. The open structure likely leads to improved intertube coupling that enhances exciton transport within the (7,5) films, consistent with the results of our pump-probe measurements.

  15. Transportation Secure Data Center: Real-World Data for Value Pricing and Tolling Research (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2013-01-01

    The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database provides free-of-charge web-based access to valuable transportation data that can be used for: Location and time-of-day variable tolling research, Mileage-based fee analysis, Travel demand modeling and transit planning, Congestion mitigation research, and Validating transportation data from other sources. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

  16. Tuning thermal transport in ultrathin silicon membranes by surface nanoscale engineering.

    Science.gov (United States)

    Neogi, Sanghamitra; Reparaz, J Sebastian; Pereira, Luiz Felipe C; Graczykowski, Bartlomiej; Wagner, Markus R; Sledzinska, Marianna; Shchepetov, Andrey; Prunnila, Mika; Ahopelto, Jouni; Sotomayor-Torres, Clivia M; Donadio, Davide

    2015-04-28

    A detailed understanding of the connections of fabrication and processing to structural and thermal properties of low-dimensional nanostructures is essential to design materials and devices for phononics, nanoscale thermal management, and thermoelectric applications. Silicon provides an ideal platform to study the relations between structure and heat transport since its thermal conductivity can be tuned over 2 orders of magnitude by nanostructuring. Combining realistic atomistic modeling and experiments, we unravel the origin of the thermal conductivity reduction in ultrathin suspended silicon membranes, down to a thickness of 4 nm. Heat transport is mostly controlled by surface scattering: rough layers of native oxide at surfaces limit the mean free path of thermal phonons below 100 nm. Removing the oxide layers by chemical processing allows us to tune the thermal conductivity over 1 order of magnitude. Our results guide materials design for future phononic applications, setting the length scale at which nanostructuring affects thermal phonons most effectively.

  17. New efficient optimal mass transport approach for single freeform surface design

    CERN Document Server

    Bösel, Christoph

    2015-01-01

    We present a new optimal mass transport approach for the design of a continuous single freeform surface for collimated beams. By applying the law of reflection/refraction and the well-known integrability condition, it is shown that the design process in a small angle approximation can be decoupled into the calculation of a raymapping by optimal mass transport methods and the subsequent construction of the freeform surface by a steady linear advection equation. It is shown that the solution of this linear advection equation can be obtained by a decomposition into two dimensional subproblems and solving these by standard integrals. The efficiency of the method is demonstrated by applying it to two challenging design examples.

  18. Taking advantage of reduced droplet-surface interaction to optimize transport of bioanalytes in digital microfluidics.

    Science.gov (United States)

    Freire, Sergio L S; Thorne, Nathaniel; Wutkowski, Michael; Dao, Selina

    2014-11-10

    Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of "lab-on-a-chip" platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique. Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives. Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

  19. Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

    Science.gov (United States)

    Umeda, Minoru; Katagiri, Mitsuhiko; Shironita, Sayoko; Nagayama, Norio

    2016-12-01

    This paper reports the anisotropic hole transport at the triphenylamine-derivative single crystal surface prepared by a solution method. Triphenylamine derivatives are commonly used in a hole-transport material for organic photoconductors of laser-beam printers, in which the materials are used as an amorphous form. For developing organic photovoltaics using the photoconductor's technology, preparation of a single crystal seems to be a specific way by realizing the high mobility of an organic semiconductor. In this study, a single crystal of 4-(2,2-diphenylethenyl)-N,N-bis(4-methylphenyl)-benzenamine (TPA) was prepared and its anisotropic hole-transport property measured. First, the hole-transport property of the TPA was investigated based on its chemical structure and electrochemical redox characteristics. Next, a large-scale single crystal formation at a high rate was developed by employing a solution method based on its solubility and supersolubility curves. The grown TPA was found to be a single crystal based on the polarization micrograph observation and crystallographic analysis. For the TPA single crystal, an anisotropic surface conduction was found, which was well explained by its molecular stack structure. The measured current in the long-axis direction is one order of magnitude greater than that of amorphous TPA.

  20. Surface plasmon enhanced quantum transport in a hybrid metal nanoparticle array

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lin; Nan, Yali; Xu, Shang; Zhang, Sishi; Han, Min, E-mail: sjhanmin@nju.edu.cn

    2014-07-18

    Hybrid Pd–Ag nanoparticle arrays composed of randomly distributed Pd nanoparticles in dense packing and a small number of dispersed Ag nanoparticles were fabricated with controlled coverage. Photo-enhanced conductance was observed in the nanoparticle arrays. Largest enhancement, which can be higher than 20 folds, was obtained with 450 nm light illumination. This wavelength was found to correlate with the surface plasmon resonance of the Ag nanoparticles. Electron transport measurements showed there were significant Coulomb blockade in the nanoparticle arrays and the blockade could be overcome with the surface plasmon enhanced local field of Ag nanoparticles induced by light illumination. - Highlights: • We study photo-enhanced electron conductance of a hybrid Pd–Ag nanoparticle array. • The light-induced conductance enhancement is as high as 20 folds at 10 K. • The enhancement is correlate with the surface plasmon resonance of Ag nanoparticles. • Coulomb blockades is overcome with the surface plasmon enhanced local field.

  1. Density wave like transport anomalies in surface doped Na2IrO3

    Directory of Open Access Journals (Sweden)

    Kavita Mehlawat

    2017-05-01

    Full Text Available We report that the surface conductivity of Na2IrO3 crystal is extremely tunable by high energy Ar plasma etching and can be tuned from insulating to metallic with increasing etching time. Temperature dependent electrical transport for the metallic samples show signatures of first order phase transitions which are consistent with charge or spin density wave like phase transitions predicted recently. Additionally, grazing-incidence small-angle x-ray scattering (GISAXS reveal that the room temperature surface structure of Na2IrO3 does not change after plasma etching.

  2. Surface and transport properties of Cu-Sn-Ti liquid alloys

    Institute of Scientific and Technical Information of China (English)

    R. Novakovic; E. Ricci; S. Amore; T. Lanata

    2006-01-01

    The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and Sn-Ti subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattce theory (QLT). This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

  3. Transporting ideas between marine and social sciences: experiences from interdisciplinary research programs

    Directory of Open Access Journals (Sweden)

    Lucy M. Turner

    2017-03-01

    Full Text Available The oceans comprise 70% of the surface area of our planet, contain some of the world’s richest natural resources and are one of the most significant drivers of global climate patterns. As the marine environment continues to increase in importance as both an essential resource reservoir and facilitator of global change, it is apparent that to find long-term sustainable solutions for our use of the sea and its resources and thus to engage in a sustainable blue economy, an integrated interdisciplinary approach is needed. As a result, interdisciplinary working is proliferating. We report here our experiences of forming interdisciplinary teams (marine ecologists, ecophysiologists, social scientists, environmental economists and environmental law specialists to answer questions pertaining to the effects of anthropogenic-driven global change on the sustainability of resource use from the marine environment, and thus to transport ideas outwards from disciplinary confines. We use a framework derived from the literature on interdisciplinarity to enable us to explore processes of knowledge integration in two ongoing research projects, based on analyses of the purpose, form and degree of knowledge integration within each project. These teams were initially focused around a graduate program, explicitly designed for interdisciplinary training across the natural and social sciences, at the Gothenburg Centre for Marine Research at the University of Gothenburg, thus allowing us to reflect on our own experiences within the context of other multi-national, interdisciplinary graduate training and associated research programs.

  4. Stochastic model for photoinduced surface relief grating formation through molecular transport in polymer films.

    Energy Technology Data Exchange (ETDEWEB)

    Juan, M.; Plain, J.; Bachelot, R.; Royer, P.; Gray, S. K.; Wiederrecht, G. P.; Univ. de Technologie de Troyes

    2008-09-01

    We use a stochastic model to study photoinduced surface relief grating (SRG) formation due to molecular transport in azobenzene polymer films. The model is shown to reproduce the essential experimental features of SRG formation. In particular, it predicts SRG formation under both p and s polarizations, and the double peaked topographies that can occur at early times of the process. The evolving molecular positions and orientations during exposure are also followed, providing a useful mechanistic picture of SRG dynamics.

  5. Transportation-Driven Mars Surface Operations Supporting an Evolvable Mars Campaign

    Science.gov (United States)

    Toups, Larry; Brown, Kendall; Hoffman, Stephen J.

    2015-01-01

    This paper describes the results of a study evaluating options for supporting a series of human missions to a single Mars surface destination. In this scenario the infrastructure emplaced during previous visits to this site is leveraged in following missions. The goal of this single site approach to Mars surface infrastructure is to enable "Steady State" operations by at least 4 crew for up to 500 sols at this site. These characteristics, along with the transportation system used to deliver crew and equipment to and from Mars, are collectively known as the Evolvable Mars Campaign (EMC). Information in this paper is presented in the sequence in which it was accomplished. First, a logical buildup sequence of surface infrastructure was developed to achieve the desired "Steady State" operations on the Mars surface. This was based on a concept of operations that met objectives of the EMC. Second, infrastructure capabilities were identified to carry out this concept of operations. Third, systems (in the form of conceptual elements) were identified to provide these capabilities. This included top-level mass, power and volume estimates for these elements. Fourth, the results were then used in analyses to evaluate three options (18t, 27t, and 40t landed mass) of Mars Lander delivery capability to the surface. Finally, Mars arrival mass estimates were generated based upon the entry, descent, and landing requirements for inclusion in separate assessments of in-space transportation capabilities for the EMC.

  6. River stage influences on uranium transport in a hydrologically dynamic groundwater-surface water transition zone: U TRANSPORT IN A GROUNDWATER-SURFACE WATER TRANSITION ZONE

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M. [Pacific Northwest National Laboratory, Richland Washington USA; Chen, Xingyuan [Pacific Northwest National Laboratory, Richland Washington USA; Murray, Chris [Pacific Northwest National Laboratory, Richland Washington USA; Hammond, Glenn [Sandia National Laboratories, Albuquerque New Mexico USA

    2016-03-01

    A tightly spaced well-field within a groundwater uranium (U) plume in the groundwater-surface water transition zone was monitored for a three year period for groundwater elevation and dissolved solutes. The plume discharges to the Columbia River, which displays a dramatic spring stage surge resulting from mountain snowmelt. Groundwater exhibits a low hydrologic gradient and chemical differences with river water. River water intrudes the site in spring. Specific aims were to assess the impacts of river intrusion on dissolved uranium (Uaq), specific conductance (SpC), and other solutes, and to discriminate between transport, geochemical, and source term heterogeneity effects. Time series trends for Uaq and SpC were complex and displayed large temporal well-to well variability as a result of water table elevation fluctuations, river water intrusion, and changes in groundwater flow directions. The wells were clustered into subsets exhibiting common temporal behaviors resulting from the intrusion dynamics of river water and the location of source terms. Concentration hot spots were observed in groundwater that varied in location with increasing water table elevation. Heuristic reactive transport modeling with PFLOTRAN demonstrated that mobilized U was transported between wells and source terms in complex trajectories, and was diluted as river water entered and exited the groundwater system. While uranium time-series concentration trends varied significantly from year to year as a result of climate-caused differences in the spring hydrograph, common and partly predictable response patterns were observed that were driven by water table elevation, and the extent and duration of the river water intrusion event.

  7. Passive scalar transport to and from the surface of a Pocillopora coral colony

    Science.gov (United States)

    Hossain, Md Monir; Staples, Anne

    2016-11-01

    Three-dimensional simulations of flow through a single Pocillopora coral colony were performed to examine the interaction between the flow conditions and scalar transport near a coral colony. With corals currently undergoing a third global bleaching event, a fuller understanding of the transport of nutrients, weak temperature gradients, and other passive scalars to and from the coral polyp tissue is more important than ever. The complex geometry of a coral colony poses a significant challenge for numerical simulation. To simplify grid generation and minimize computational cost, the immersed boundary method was implemented. Large eddy simulation was chosen as the framework to capture the turbulent flow field in the range of realistic Reynolds numbers of 5,000 to 30,000 and turbulent Schmidt numbers of up to 1,000. Both uniform and oscillatory flows through the colony were investigated. Significant differences were found between the cases when the scalar originated at the edge of the flow domain and was transported into the colony, versus when the scalar originated on the surface of the colony and was transported away from the coral. The domain-to-colony transport rates were found to be orders of magnitude higher than the colony-to-domain rates.

  8. The research on natural gas pipeline transportation price formulation method

    OpenAIRE

    YU Wenjia; Ma, Yan

    2014-01-01

    This paper will introduce a method of natural gas pipeline transportation price on the basis of two-part tariff.Distance,investment and income have been taken into consideration.The total fee is divided into three parts:reservation fee,usage fee and peak-load regulation fee.Because there are different types of users in the natural gas market who show great difference in the continuity and reliability of gas supply,capacity of bearing price,elastic demand and balance use of gas,according to th...

  9. Role of R&D (research and development) in transport infrastructure in South Africa

    CSIR Research Space (South Africa)

    Rust, FC

    2008-07-01

    Full Text Available The current status of South Africa's infrastructure is analysed with emphasis on transport infrastructure. The role of Science, Engineering and Technology as well as associated Research and Development in supporting the development of sustainable...

  10. Towards a Common Research Strategic Roadmap for the Transportation Sector in Europe and beyond

    Directory of Open Access Journals (Sweden)

    Evangelos Bekiaris

    2013-08-01

    Full Text Available DETRA (Developing a European Transport Research Alliance is a 7th Framework project, whose concept derived from the so-called Lyon Declaration and concerns the deepening of the European Research Area objectives in transport in order to address the Grand Challenges. Key priorities of this Alliance is to examine the strengths, weaknesses, opportunities and threats (SWOT in the domain and develop common understanding and approaches to reducing fragmentation and overcoming barriers. The DETRA project aimed to meet and exceed the requirements and objectives of the call for an Analysis of the state of ERA development within the transport domain and to develop recommendations for the EC, member states and other stakeholders as well as for the DETRA partner organizations themselves. In this study, particular emphasis is given to the part of DETRA concerning the development of a single trans- European research program, which can be used as a compass for the future research activities of the whole transportation area.

  11. Basic Research Needs for Clean and Efficient Combustion of 21st Century Transportation Fuels

    Energy Technology Data Exchange (ETDEWEB)

    McIlroy, A.; McRae, G.; Sick, V.; Siebers, D. L.; Westbrook, C. K.; Smith, P. J.; Taatjes, C.; Trouve, A.; Wagner, A. F.; Rohlfing, E.; Manley, D.; Tully, F.; Hilderbrandt, R.; Green, W.; Marceau, D.; O' Neal, J.; Lyday, M.; Cebulski, F.; Garcia, T. R.; Strong, D.

    2006-11-01

    To identify basic research needs and opportunities underlying utilization of evolving transportation fuels, with a focus on new or emerging science challenges that have the potential for significant long-term impact on fuel efficiency and emissions.

  12. RESULTS OF RESEARCH OF AIR POLLUTION BY AUTOMOBILE TRANSPORT IN THE STREETS OF KHARKIV

    Directory of Open Access Journals (Sweden)

    Lezhneva, E.

    2013-06-01

    Full Text Available Results of the research of the atmospheric air of residential area roadside territory at functioning of motor transport are presented. Architectural and planning activities to improve the environmental performance of the local area of Kharkiv are offered.

  13. A field study of colloid transport in surface and subsurface flows

    Science.gov (United States)

    Zhang, Wei; Tang, Xiang-Yu; Xian, Qing-Song; Weisbrod, Noam; Yang, Jae E.; Wang, Hong-Lan

    2016-11-01

    Colloids have been recognized to enhance the migration of strongly-sorbing contaminants. However, few field investigations have examined combined colloid transport via surface runoff and subsurface flows. In a headwater catchment of the upper Yangtze River, a 6 m (L) by 4 m (W) sloping (6°) farmland plot was built by cement walls to form no-flow side boundaries. The plot was monitored in the summer of 2014 for the release and transport of natural colloids via surface runoff and subsurface flows (i.e., the interflow from the soil-mudrock interface and fracture flow from the mudrock-sandstone interface) in response to rain events. The water sources of the subsurface flows were apportioned to individual rain events using a two end-member model (i.e., mobile pre-event soil water extracted by a suction-cup sampler vs. rainwater (event water)) based on δ18O measurements. For rain events with high preceding soil moisture, mobile pre-event soil water was the main contributor (generally >60%) to the fracture flow. The colloid concentration in the surface runoff was 1-2 orders of magnitude higher than that in the subsurface flows. The lowest colloid concentration was found in the subsurface interflow, which was probably the result of pore-scale colloid straining mechanisms. The rainfall intensity and its temporal variation govern the dynamics of the colloid concentrations in both surface runoff and subsurface flows. The duration of the antecedent dry period affected not only the relative contributions of the rainwater and the mobile pre-event soil water to the subsurface flows but also the peak colloid concentration, particularly in the fracture flow. The rain period because their transport in association with colloids may occur rapidly over long distances via both surface runoff and subsurface flows with rainfall.

  14. Nuclear Fusion Research Understanding Plasma-Surface Interactions

    CERN Document Server

    Clark, Robert E.H

    2005-01-01

    It became clear in the early days of fusion research that the effects of the containment vessel (erosion of "impurities") degrade the overall fusion plasma performance. Progress in controlled nuclear fusion research over the last decade has led to magnetically confined plasmas that, in turn, are sufficiently powerful to damage the vessel structures over its lifetime. This book reviews current understanding and concepts to deal with this remaining critical design issue for fusion reactors. It reviews both progress and open questions, largely in terms of available and sought-after plasma-surface interaction data and atomic/molecular data related to these "plasma edge" issues.

  15. Research into surface wave phenomena in sedimentary basins

    Science.gov (United States)

    Wojcik, G. L.; Isenberg, J.; Ma, F.; Richardson, E.

    1981-12-01

    This study is a continuation of an engineering seismology research effort prompted by the sensitivity of guidance sets in Minuteman Wing V to distant earthquakes. An earlier report considers the probable cause of anomalous patterns of seismic alarms triggered by two North American earthquakes. This report extends the previous study by examining the propagation of surface waves from the 1975 Pocatello Valley, Idaho earthquake sequence across Wyoming to Wing V. In addition, the more general question of surface wave phenomena in sedimentary basins is addressed, particularly the effect of laterally inhomogeneous (dipping) basin-bedrock interfaces. Findings indicate that fundamental and first overtone surface waves are significantly modified by the travel path. In contrast, higher modes are relatively unchanged by the travel path, and affect Wing V in much the same way as body waves considered in the previous study.

  16. [Toxicity research status of benzalkonium chloride on ocular surface].

    Science.gov (United States)

    Huang, Caihong; Chen, Wensheng; Chen, Yongxiong; Liu, Zuguo

    2014-04-01

    Benzalkonium chloride (BAC) is the most commonly used preservative in ophthalmic preparations.So far large bodies of clinical and experimental studies have shown that use of topical drugs containing BAC can induce a series of ocular surface diseases, such as apoptosis.However, recently, some clinical studies have shown that ocular toxicity in patients treated with eye drops containing BAC has not apparent correlated with BAC.Some scholars consider that the limitations of the research lead people to recognize the BAC toxicity exaggeratedly.Here we summarize numerous clinical and experimental studies of BAC in the past few years, and focus on reviewing recent researches of the toxic effect of BAC on ocular surface.

  17. Estimating source-attributable health impacts of ambient fine particulate matter exposure: global premature mortality from surface transportation emissions in 2005

    Science.gov (United States)

    Chambliss, S. E.; Silva, R.; West, J. J.; Zeinali, M.; Minjares, R.

    2014-10-01

    Exposure to ambient fine particular matter (PM2.5) was responsible for 3.2 million premature deaths in 2010 and is among the top ten leading risk factors for early death. Surface transportation is a significant global source of PM2.5 emissions and a target for new actions. The objective of this study is to estimate the global and national health burden of ambient PM2.5 exposure attributable to surface transportation emissions. This share of health burden is called the transportation attributable fraction (TAF), and is assumed equal to the proportional decrease in modeled ambient particulate matter concentrations when surface transportation emissions are removed. National population-weighted TAFs for 190 countries are modeled for 2005 using the MOZART-4 global chemical transport model. Changes in annual average concentration of PM2.5 at 0.5 × 0.67 degree horizontal resolution are based on a global emissions inventory and removal of all surface transportation emissions. Global population-weighted average TAF was 8.5 percent or 1.75 μg m-3 in 2005. Approximately 242 000 annual premature deaths were attributable to surface transportation emissions, dominated by China, the United States, the European Union and India. This application of TAF allows future Global Burden of Disease studies to estimate the sector-specific burden of ambient PM2.5 exposure. Additional research is needed to capture intraurban variations in emissions and exposure, and to broaden the range of health effects considered, including the effects of other pollutants.

  18. A physically-based integrated numerical model for flow, upland erosion, and contaminant transport in surface-subsurface systems

    Institute of Scientific and Technical Information of China (English)

    HE ZhiGuo; WU WeiMing

    2009-01-01

    This paper presents a physically-based integrated hydrologic model that can simulate the rain-fall-induced 2D surface water flow, 3D variably saturated subsurface flow, upland soil erosion and transport, and contaminant transport in the surface-subsurface system of a watershed.The model couples surface and subsurface flows based on the assumption of continuity conditions of pressure head and exchange flux at the ground, considering infiltration and evapotranspiration.The upland rill/interrill soil erosion and transport are simulated using a non-equilibrium transport model.Con-taminant transport in the integrated surface and subsurface domains is simulated using advec-tion-diffusion equations with mass changes due to sediment sorption and desorption and exchanges between two domains due to infiltration, diffusion, and bed change.The model requires no special treatments at the interface of upland areas and streams and is suitable for wetland areas and agricul-tural watersheds with shallow streams.

  19. Addressing transportation energy and environmental impacts: technical and policy research directions

    Energy Technology Data Exchange (ETDEWEB)

    Weissenberger, S.; Pasternak, A.; Smith, J.R.; Wallman, H.

    1995-08-01

    The Lawrence Livermore National Laboratory (LLNL) is establishing a local chapter of the University of California Energy Institute (UCEI). In order to most effectively contribute to the Institute, LLNL sponsored a workshop on energy and environmental issues in transportation. This workshop took place in Livermore on August 10 and brought together researchers from throughout the UC systems in order to establish a joint LLNL-UC research program in transportation, with a focus on energy and environmental impacts.

  20. Transforming ocular surface stem cell research into successful clinical practice

    Directory of Open Access Journals (Sweden)

    Virender S Sangwan

    2014-01-01

    Full Text Available It has only been a quarter of a century since the discovery of adult stem cells at the human corneo-scleral limbus. These limbal stem cells are responsible for generating a constant and unending supply of corneal epithelial cells throughout life, thus maintaining a stable and uniformly refractive corneal surface. Establishing this hitherto unknown association between ocular surface disease and limbal dysfunction helped usher in therapeutic approaches that successfully addressed blinding conditions such as ocular burns, which were previously considered incurable. Subsequent advances in ocular surface biology through basic science research have translated into innovations that have made the surgical technique of limbal stem cell transplantation simpler and more predictable. This review recapitulates the basic biology of the limbus and the rationale and principles of limbal stem cell transplantation in ocular surface disease. An evidence-based algorithm is presented, which is tailored to clinical considerations such as laterality of affliction, severity of limbal damage and concurrent need for other procedures. Additionally, novel findings in the form of factors influencing the survival and function of limbal stem cells after transplantation and the possibility of substituting limbal cells with epithelial stem cells of other lineages is also discussed. Finally this review focuses on the future directions in which both basic science and clinical research in this field is headed.

  1. Examining Lagrangian surface transport during a coastal upwelling in the Gulf of Finland, Baltic Sea

    Science.gov (United States)

    Delpeche-Ellmann, Nicole; Mingelaitė, Toma; Soomere, Tarmo

    2017-07-01

    We employ in-situ surface drifters and satellite derived sea surface temperature data to examine the impact that an upwelling event may have on mixing and Lagrangian transport of surrounding surface waters. The test area is located near the southern coast of the Gulf of Finland where easterly winds are known to trigger intense coastal upwellings. The analysis is based on the comparison of motions of three drifters that follow the currents in the uppermost layer with a thickness of 2 m with MODIS-based sea surface temperature data and high-quality open sea wind time series. The presence of an upwelling event superseded the classic Ekman-type drift of the surface layer and considerably slowed down the average speed of surface currents in the region affected by the upwelled cold water jet and its filaments. The drifters tended to stay amidst the surrounding surface waters. The properties of mixing were evaluated using the daily rate of temperature change along several transects. The upwelled cooler water largely kept its identity during almost the entire duration of the upwelling event. Intense mixing started at a later stage of the upwelling and continued after the end of the event when the winds that have driven the entire process began to subside.

  2. Transport and deposition of nitrogen oxides and ozone in the atmospheric surface layer

    Science.gov (United States)

    Li, Yongxian

    Tropospheric ozone is an important photochemical air pollutant, which increases respiratory-related diseases, decreases crop yields, and causes other environmental problems. This research has focused on the measurement of soil biogenic emissions of nitric oxide (NO), one of the precursors for ozone formation, from intensively managed soils in the Southeast US, and examined the transport and deposition of NOx (NO + NO2) and ozone in the atmospheric surface layer, and the effects of NO emissions and its chemical reactions on ozone flux and deposition to the earth's surface. Emissions of nitric oxide were measured from an intensively managed agricultural soil, in the lower coastal plain of North Carolina (near Plymouth, NC), using a dynamic chamber technique. Measurements of soil NO emissions in several crop canopies were conducted at four different sites in North Carolina during late spring and summer of 1994-1996. The turbulent fluxes of NO2 and O3 at 5 m and 10 m above the ground were measured using the eddy-correlation technique near Plymouth, NC during late spring of 1995 and summer of 1996, concurrent with measurements of soil NO emissions using the dynamic chamber system. Soil NO emission from within the corn field was high averaging approximately 35 ng N/m2/s during the measurement period of 1995. In another study, vertical measurements of ozone were made on a 610 m tall tower located 15 km Southeast of Raleigh, NC during the summers of 1993-1997, as part of an effort by the State of North Carolina to develop a State Implementation Plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area. A strong correlation was observed between the nighttime and early morning ozone concentrations in the residual layer (CR) above the NBL and the maximum ground level concentration (C o max) the following afternoon. Based on this correlation, an empirical regression equation (Co max = 27.67*exp(0.016 CR)) was developed for predicting maximum ground level ozone

  3. Research on new-style flexure supports method for large-aperture transport mirror mounting

    Science.gov (United States)

    Quan, Xusong; Zhang, Zheng; Xiong, Zhao; Wang, Hui; Yuan, Xiaodong; Liu, Changchun

    2016-10-01

    In high-power solid-state laser facility (SG-III), focusing laser beams into the target center with precision better than 50 microns (RMS) is dependent on the stringent specifications of thousands of large-aperture transport mirror units and is a huge challenge on the surface aberration control of mirrors. The current mirror's mounting techniques with screw fastening loads has several engineering conundrums - low control precision for loads (higher scatter even +/-30%), and low assembly-rectification efficiency ( 100 screws). To improve the current screw-fastening method, a new-style flexure supports method, which has a wonderful performance on uniform control of the external loads and only uses 30 screws, is proposed to mount the mirror (size: 610mm×440mm×85mm). With theoretical modeling and FEM analysis, the impacts of mounting loads on mirror's surface aberrations are analyzed and discussed in detail, and the flexure supports system is designed. Finally, with experimental research and case studies, the proposed flexure supports method shows a powerful performance on even control precision of external loads with scatter even less than +/-10%, which is a promising mounting process to replace the threaded fasteners mounting the large-aperture optics. These improvements can lay a foundation for mounting process consistency, robustness, and assembly-rectification efficiency of large optical component.

  4. Intermodal safety research needs report of the sixth workshop on national transportation problems

    Energy Technology Data Exchange (ETDEWEB)

    Warshawer, A.J. (ed.)

    1976-04-01

    This conference brought together DOT policymakers, university principal investigators and other professionals to consider the intermodal safety research requirements of the Department of Transportation. The objectives of the conference were: (1) to highlight safety problems and needed transportation safety research identified by DOT modal safety managers and to stimulate university or university/industry teams to respond with research proposals which emphasize multi-modal applicability and a system view; and (2) to provide a forum for university research groups to inform DOT safety managers of promising new directions in transportation safety research and new tools with which to address safety related problems. The conference addressed the research requirements for safety as identified by the Statement of National Transportation Policy and by the modal safety managers in three principal contexts, each a workshop panel: I, Inter-Institutional Problems of Transportation Safety. Problems were described as: Federal-State, local; Federal-Industry; Federal-Public, Consumer groups. II, Goal Setting and Planning for Transportation Safety Programs. Issues were: modifying risk behavior, safety as a social value, and involving citizens in development of standards as a way of increasing probability of achieving program objectives. III, DOT Information, Management, and Evaluation Systems Requirements. Needs were: data requirements and analytic tools for management of safety programs.

  5. Lessons learned from bacterial transport research at the South Oyster Site

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, T.; Hubbard, S.S.; Onstott, T.C.; DeFlaun, M.F.

    2011-04-01

    This paper provides a review of bacterial transport experiments conducted by a multi-investigator, multi-institution, multi-disciplinary team of researchers under the auspices of the U. S. Department of Energy (DOE). The experiments were conducted during the time period 1999-2001 at a field site near the town of Oyster, Virginia known as the South Oyster Site, and included four major experimental campaigns aimed at understanding and quantifying bacterial transport in the subsurface environment. Several key elements of the research are discussed here: (1) quantification of bacterial transport in physically, chemically and biologically heterogeneous aquifers, (2) evaluation of the efficacy of conventional colloid filtration theory, (3) scale effects in bacterial transport, (4) development of new methods for microbial enumeration and screening for low adhesion strains, (5) application of novel hydrogeophysical techniques for aquifer characterization, and (6) experiences regarding management of a large field research effort. Lessons learned are summarized in each of these areas. The body of literature resulting from South Oyster Site research has been widely cited and continues to influence research into the controls exerted by aquifer heterogeneity on reactive transport (including microbial transport). It also served as a model (and provided valuable experience) for subsequent and ongoing highly-instrumented field research efforts conducted by DOE-sponsored investigators.

  6. Aviation safety research and transportation/hazard avoidance and elimination

    Science.gov (United States)

    Sonnenschein, C. M.; Dimarzio, C.; Clippinger, D.; Toomey, D.

    1976-01-01

    Data collected by the Scanning Laser Doppler Velocimeter System (SLDVS) was analyzed to determine the feasibility of the SLDVS for monitoring aircraft wake vortices in an airport environment. Data were collected on atmospheric vortices and analyzed. Over 1600 landings were monitored at Kennedy International Airport and by the end of the test period 95 percent of the runs with large aircraft were producing usable results in real time. The transport was determined in real time and post analysis using algorithms which performed centroids on the highest amplitude in the thresholded spectrum. Making use of other parameters of the spectrum, vortex flow fields were studied along with the time histories of peak velocities and amplitudes. The post analysis of the data was accomplished with a CDC-6700 computer using several programs developed for LDV data analysis.

  7. The research on natural gas pipeline transportation price formulation method

    Directory of Open Access Journals (Sweden)

    YU Wenjia

    2014-02-01

    Full Text Available This paper will introduce a method of natural gas pipeline transportation price on the basis of two-part tariff.Distance,investment and income have been taken into consideration.The total fee is divided into three parts:reservation fee,usage fee and peak-load regulation fee.Because there are different types of users in the natural gas market who show great difference in the continuity and reliability of gas supply,capacity of bearing price,elastic demand and balance use of gas,according to the method,the different types of users can pay reasonable fee.This method not only considers the investment income recovery but also considers the different types of users paying a reasonable fee.We hope the new pricing model can give a reference to the development of China's natural gas industry.

  8. Research on Transport Properties of HFC-227ea

    Institute of Scientific and Technical Information of China (English)

    Lin Shi; Xiaojun Liu; Yuanyuan Duan; Lizhong Han; Mingshan Zhu

    2001-01-01

    HFC-227ea(1,1,1,2,3,3,3-heptafluoropropane) is considered as a promising refrigerant alternative, especially as a component in mixtures, to replace to CFC-12, HCFC-22 and R502. But reliable transport properties data for HFC-227ea are very limited. In this paper, experimental data of viscosity along the saturation line and gaseous thermal conductivity of HFC-227ea are given. The viscosity of HFC-227ea was measured with a capillary viscometer at temperatures between 263.15 K and 333.15 K along the saturation line and its uncertainty of the results is estimated to be no more than +3%. The thermal conductivity of gaseous HFC-227ea was also measured with a transient hot-wire instrument at temperatures between 259.28 K and 341.75 K and pressures up to 1.289MPa, and its uncertainty of the results is estimated to be less than +1%.

  9. Research requirements for a real-time flight measurements and data analysis system for subsonic transport high-lift research

    Science.gov (United States)

    Whitehead, Julia H.; Harris, Franklin K.; Lytle, Carroll D.

    1993-01-01

    A multiphased research program to obtain detailed flow characteristics on a multielement high-lift flap system is being conducted on the Transport Systems Research Vehicle (B737-100 aircraft) at NASA Langley Research Center. Upcoming flight tests have required the development of a highly capable and flexible flight measurement and data analysis instrumentation system. This instrumentation system will be more comprehensive than any of the systems used on previous high-lift flight experiment at NASA Langley. The system will provide the researcher near-real-time information for decision making needed to modify a flight test in order to further examine unexpected flow conditions. This paper presents the research requirements and instrumentation design concept for an upcoming flight experiment for the subsonic transport high-lift research program. The flight experiment objectives, the measurement requirements, the data acquisition system, and the onboard data analysis and display capabilities are described.

  10. Emergent Conformal Symmetry and Geometric Transport Properties of Quantum Hall States on Singular Surfaces

    Science.gov (United States)

    Can, T.; Chiu, Y. H.; Laskin, M.; Wiegmann, P.

    2016-12-01

    We study quantum Hall states on surfaces with conical singularities. We show that the electronic fluid at the cone tip possesses an intrinsic angular momentum, which is due solely to the gravitational anomaly. We also show that quantum Hall states behave as conformal primaries near singular points, with a conformal dimension equal to the angular momentum. Finally, we argue that the gravitational anomaly and conformal dimension determine the fine structure of the electronic density at the conical point. The singularities emerge as quasiparticles with spin and exchange statistics arising from adiabatically braiding conical singularities. Thus, the gravitational anomaly, which appears as a finite size correction on smooth surfaces, dominates geometric transport on singular surfaces.

  11. Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins

    Science.gov (United States)

    Coupe, R.H.; Kalkhoff, S.J.; Capel, P.D.; Gregoire, C.

    2012-01-01

    Background: Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used widely throughout the world in the production of many crops and is heavily used on soybeans, corn and cotton. Glyphosate is used in almost all agricultural areas of the United States, and the agricultural use of glyphosate has increased from less than 10 000 Mg in 1992 to more than 80 000 Mg in 2007. The greatest intensity of glyphosate use is in the midwestern United States, where applications are predominantly to genetically modified corn and soybeans. In spite of the increase in usage across the United States, the characterization of the transport of glyphosate and its degradate aminomethylphosphonic acid (AMPA) on a watershed scale is lacking. Results: Glyphosate and AMPA were frequently detected in the surface waters of four agricultural basins. The frequency and magnitude of detections varied across basins, and the load, as a percentage of use, ranged from 0.009 to 0.86% and could be related to three general characteristics: source strength, rainfall runoff and flow route. Conclusions: Glyphosate use in a watershed results in some occurrence in surface water; however, the watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff and a flow route that does not include transport through the soil. ?? 2011 Society of Chemical Industry.

  12. Modeling pollutant transport in overland flow over non-planar and non-homogenous infiltrating surfaces

    Institute of Scientific and Technical Information of China (English)

    Zhi-guo HE; Gokmen TAYFUR; Qi-hua RAN; Hao-xuan WENG

    2013-01-01

    Pollutant transport in overland flow over surfaces with spatially varying microtopography,roughness,and infiltration was investigated using the diffusion wave equation and transport rate-based equation.The finite volume method in space and an implicit backward difference scheme in time were employed in the numerical solution of the 2D governing equations.The developed model was first tested against an analytical solution and an experimental study involving overland flow and the associated pollutant transport,subsequently a series of numerical tests were carried out.Non-point source pollution was investigated under spatially varying microtopography,roughness,and infiltration.The simulation results showed that microtopography and roughness were the dominant factors causing significant spatial variations in solute concentration.When the spatially varying microtopography was replaced by a smooth surface,the result was an overestimation of the solute rate at the outlet of the upland.On the other hand,when the spatially varying roughness was replaced by the average roughness and spatially varying infiltration rate by the average infiltration rate,the pollutant discharge at the outlet of the upland was not significantly affected.The numerical results further showed that one cannot ignore the spatial variations of slope and roughness when investigating the local pollutant concentration distribution.

  13. The Fate and Transport of Glyphosate and AMPA into Surface Waters of Agricultural Watersheds

    Science.gov (United States)

    Coupe, R.; Kalkhoff, S.; Capel, P.; Gregoire, C.

    2010-12-01

    Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used widely throughout the world in the production of many crops, but is particularly heavily used on crops which are genetically modified to be glyphosate tolerant: predominately soybeans, corn, potatoes, and cotton. Glyphosate is used extensively in almost all agricultural areas of the United States, and annual application has increased from less than 10,000 Mg in 1992 to more than 80,000 Mg in 2007. The greatest areal use is in the Midwest where glyphosate is applied on genetically modified corn and soybeans. Although use is increasing, the characterization of glyphosate transport on the watershed scale is lacking. Glyphosate, and its degradate AMPA [aminomethylphosphoric acid], was frequently detected in the surface waters of four agricultural watersheds. The load as a percent of use of glyphosate ranged from 0.009 to 0.86 percent and can be related to three factors: source strength, hydrology, and flowpath. Glyphosate use within a watershed results in some occurrence in surface water at the part per billion level; however watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff, and a flowpath that does not include transport through the soil.

  14. Transport and dispersion of pollutants in surface impoundments: a finite element model

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.

    1980-07-01

    A surface impoundment model in finite element (SIMFE) is presented to enable the simulation of flow circulations and pollutant transport and dispersion in natural or artificial lakes, reservoirs or ponds with any number of islands. This surface impoundment model consists of two sub-models: hydrodynamic and pollutant transport models. Both submodels are simulated by the finite element method. While the hydrodynamic model is solved by the standard Galerkin finite element scheme, the pollutant transport model can be solved by any of the twelve optional finite element schemes built in the program. Theoretical approximations and the numerical algorithm of SIMFE are described. Detail instruction of the application are given and listing of FORTRAN IV source program are provided. Two sample problems are given. One is for an idealized system with a known solution to show the accuracy and partial validation of the models. The other is applied to Prairie Island for a set of hypothetical input data, typifying a class of problems to which SIMFE may be applied.

  15. Using full-mission simulation for human factors research in air transport operations

    Science.gov (United States)

    Orlady, Harry W.; Hennessy, Robert W.; Obermayer, Richard; Vreuls, Donald; Murphy, Miles R.

    1988-01-01

    This study examined state-of-the-art mission oriented simulation and its use in human factors research. Guidelines were developed for doing full-mission human factors research on crew member behavior during simulated air transport operations. The existing literature was reviewed. However, interviews with experienced investigators provided the most useful information. The fundamental scientific and practical issues of behavioral research in a simulation environment are discussed. Guidelines are presented for planning, scenario development, and the execution of behavioral research using full-mission simulation in the context of air transport flight operations . Research is recommended to enhance the validity and productivity of full-mission research by: (1) validating the need for high-fidelity simulation of all major elements in the operational environment, (2) improving methods for conducting full-mission research, and (3) examining part-task research on specific problems through the use of vehicles which contain higher levels of abstraction (and lower fidelity) of the operational environment.

  16. Preliminary Assessment of Mercury Atmosphere-Surface Exchange Parameterizations for Incorporation into Chemical Transport Models

    Science.gov (United States)

    Khan, T.; Agnan, Y.; Obrist, D.; Selin, N. E.; Urban, N. R.; Wu, S.; Perlinger, J. A.

    2015-12-01

    Inadequate representation of process-based mechanisms of exchange behavior of elemental mercury (Hg0) and decoupled treatment of deposition and emission are two major limitations of parameterizations of atmosphere-surface exchange flux commonly incorporated into chemical transport models (CTMs). Of nineteen CTMs for Hg0 exchange we reviewed (ten global, nine regional), eight global and seven regional models have decoupled treatment of Hg0 deposition and emission, two global models include no parameterization to account for emission, and the remaining two regional models include coupled deposition and emission parameterizations (i.e., net atmosphere-surface exchange). The performance of atmosphere-surface exchange parameterizations in CTMs depends on parameterization uncertainty (in terms of both accuracy and precision) and feasibility of implementation. We provide a comparison of the performance of three available parameterizations of net atmosphere-surface exchange. To evaluate parameterization accuracy, we compare predicted exchange fluxes to field measurements conducted over a variety of surfaces compiled in a recently developed global database of terrestrial Hg0 surface-atmosphere exchange flux measurements. To assess precision, we estimate the sensitivity of predicted fluxes to the imprecision in parameter input values, and compare this sensitivity to that derived from analysis of the global Hg0 flux database. Feasibility of implementation is evaluated according to the availability of input parameters, computational requirements, and the adequacy of uncertainty representation. Based on this assessment, we provide suggestions for improved treatment of Hg0 net exchange processes in CTMs.

  17. Effects of magnetic drift tangential to magnetic surfaces on neoclassical transport in non-axisymmetric plasmas

    CERN Document Server

    Matsuoka, Seikichi; Kanno, Ryutaro; Sugama, Hideo

    2015-01-01

    In evaluating neoclassical transport by radially-local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport are investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight $\\delta f$ Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas $\\rm \\textbf{1}$, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transpo...

  18. Surface oxygen vacancy and oxygen permeation flux limits of perovskite ion transport membranes

    KAUST Repository

    Hunt, Anton

    2015-09-01

    © 2015 Elsevier B.V. The mechanisms and quantitative models for how oxygen is separated from air using ion transport membranes (ITMs) are not well understood, largely due to the experimental complexity for determining surface exchange reactions at extreme temperatures (>800°C). This is especially true when fuels are present at the permeate surface. For both inert and reactive (fuels) operations, solid-state oxygen surface vacancies (δ) are ultimately responsible for driving the oxygen flux, JO2. In the inert case, the value of δ at either surface is a function of the local PO2 and temperature, whilst the magnitude of δ dictates both the JO2 and the inherent stability of the material. In this study values of δ are presented based on experimental measurements under inert (CO2) sweep: using a permeation flux model and local PO2 measurements, collected by means of a local gas-sampling probe in our large-scale reactor, we can determine δ directly. The ITM assessed was La0.9Ca0.1FeO3-δ (LCF); the relative resistances to JO2 were quantified using the pre-defined permeation flux model and local PO2 values. Across a temperature range from 825°C to 1056°C, δ was found to vary from 0.007 to 0.029 (<1%), safely within material stability limits, whilst the permeate surface exchange resistance dominates. An inert JO2 limit was identified owing to a maximum sweep surface δ, δmaxinert. The physical presence of δmaxinert is attributed to a rate limiting step shift from desorption to associative electron transfer steps on the sweep surface as PO2 is reduced. Permeate surface exchange limitations under non-reactive conditions suggest that reactive (fuel) operation is necessary to accelerate surface chemistry for future work, to reduce flux resistance and push δpast δmaxinert in a stable manner.

  19. Pavement management and weigh-in-motion. Transportation research record

    Energy Technology Data Exchange (ETDEWEB)

    Cation, K.A.; Shahin, M.Y.; Scullion, T.; Lytton, R.L.; Butt, A.A.

    1987-01-01

    The 15 papers in the report deal with the following areas: development of a preventive maintenance algorithm for use in pavement-management systems; pavement-performance prediction model using the Markov Process; roadway modeling and data conversion for a transportation-facilities information system; development of a methodology to estimate pavement maintenance and repair costs for different ranges of pavement-condition index; new techniques for modeling pavement deterioration; pavement management at the local government level; a comprehensive ranking system for local-agency pavement management; expert system as a part of pavement management; MAPCON: a pavement-evaluation data-analysis computer system; a microcomputer procedure to analyze axle load limits and pavement damage responsibility; selected results from the first three years of the Oregon automatic monitoring demonstration project; automated acquisition of truck-tire pressure data; calibration and accuracy testing of weigh-in-motion systems; accuracy and tolerances of weigh-in-motion systems; on-site calibration of weigh-in-motion systems.

  20. Electrostatic potential variation on the flux surface and its impact on impurity transport

    CERN Document Server

    García-Regaña, J M; Turkin, Y; Kleiber, R; Helander, P; Maaßberg, H; Alonso, J A; Velasco, J L

    2015-01-01

    The particle transport of impurities in magnetically confined plasmas under some conditions does not find, neither quantitatively nor qualitatively, a satisfactory theory-based explanation. This compromise the successful realization of thermo-nuclear fusion for energy production since its accumulation is known to be one of the causes that leads to the plasma breakdown. In standard reactor-relevant conditions this accumulation is in most stellarators intrinsic to the lack of toroidal symmetry, that leads to the neoclassical electric field to point radially inwards. This statement, that the standard theory allows to formulate, has been contradicted by some experiments that showed weaker or no accumulation under such conditions \\cite{Ida_pop_16_056111_2009, Yoshinuma_nf_49_062002_2009}. The charge state of the impurities makes its transport more sensitive to the electric fields. Thus, the short length scale turbulent electrostatic potential or its long wave-length variation on the flux surface $\\Phi_{1}$ -- that...

  1. Medical complications of intra-hospital patient transports: implications for architectural design and research.

    Science.gov (United States)

    Ulrich, Roger S; Zhu, Xuemei

    2007-01-01

    Literature on healthcare architecture and evidence-based design has rarely considered explicitly that patient outcomes may be worsened by intra-hospital transport (IHT), which is defined as transport of patients within the hospital. The article focuses on the effects of IHTs on patient complications and outcomes, and the implications of such impacts for designing safer, better hospitals. A review of 22 scientific studies indicates that IHTs are subject to a wide range of complications, many of which occur frequently and have distinctly detrimental effects on patient stability and outcomes. The research suggests that higher patient acuity and longer transport durations are associated with more frequent and serious IHT-related complications and outcome effects. It appears no rigorous research has compared different hospital designs and layouts with respect to having possibly differential effects on transport-related complications and worsened outcomes. Nonetheless, certain design implications can be extracted from the existing research literature, including the importance of minimizing transport delays due to restricted space and congestion, and creating layouts that shorten IHT times for high-acuity patients. Limited evidence raises the possibility that elevator-dependent vertical building layouts may increase susceptibility to transport delays that worsen complications. The strong evidence indicating that IHTs trigger complications and worsen outcomes suggests a powerful justification for adopting acuity-adaptable rooms and care models that substantially reduce transports. A program of studies is outlined to address gaps in knowledge.Key WordsPatient transports, transports within hospitals, patient safety, evidence-based design, hospital design, healthcare architecture, intra-hospital transport complications, acuity-adaptable care, elevators, outcomes.

  2. Phosphorus transport with runoff of simulated rainfall from purple-soil cropland of different surface conditions

    Institute of Scientific and Technical Information of China (English)

    GAO Yang; ZHANG Jin-zhong; ZHU Bo; ZHOU Pei; MIAO Chi-yuan; WANG Tao

    2008-01-01

    We investigated the patterns of phosphorus transport from purple-soil cropland of 5° and 10° slopes with bare and vegetated surfaces, respectively. Each type of land was tested under a simulated moderate rainfall of 0.33 mm/min, a downfall of 0.90 mm/min, and a rainstorm of 1.86 mm/min. Runoff dynamics and changes in the export amount of phosphorus are influenced by the rainfall intensity, the slope and surface conditions of cropland. The vegetation diverts rain water from the surface into soil and helps the formation of a subsurface runoff, but has little influence on runoff process at the same sloping degree. Vegetated soil has a smaller phosphorous loss, particularly much less in the particulate form. A heavier rainfall flushes away more phosphorous. Rainwater percolating soil carries more dissolved phosphorous than particulate phosphorous. Understanding the patterns of phosphorous transport under various conditions from purple soil in the middle of Sichuan basin is helpful for developing countermeasures against non-point-source pollution resulting in the eutrophication of water bodies in this region that could, if not controlled properly, deteriorate the water quality of the Three Gorges Reservoir.

  3. A propagating ATPase gradient drives transport of surface-confined cellular cargo.

    Science.gov (United States)

    Vecchiarelli, Anthony G; Neuman, Keir C; Mizuuchi, Kiyoshi

    2014-04-01

    The faithful segregation of duplicated genetic material into daughter cells is critical to all organisms. In many bacteria, the segregation of chromosomes involves transport of "centromere-like" loci over the main body of the chromosome, the nucleoid, mediated by a two-protein partition system: a nonspecific DNA-binding ATPase, ParA, and an ATPase stimulator, ParB, which binds to the centromere-like loci. These systems have previously been proposed to function through a filament-based mechanism, analogous to actin- or microtubule-based movement. Here, we reconstituted the F-plasmid partition system using a DNA-carpeted flow cell as an artificial nucleoid surface and magnetic beads coated with plasmid partition complexes as surface-confined cargo. This minimal system recapitulated directed cargo motion driven by a surface ATPase gradient that propagated with the cargo. The dynamics are consistent with a diffusion-ratchet model, whereby the cargo dynamically establishes, and interacts with, a concentration gradient of the ATPase. A chemophoresis force ensues as the cargo perpetually chases the ATPase gradient, allowing the cargo to essentially "surf" the nucleoid on a continuously traveling wave of the ATPase. Demonstration of this non-filament-based motility mechanism in a biological context establishes a distinct class of motor system used for the transport and positioning of large cellular cargo.

  4. Rayleigh surface waves, phonon mode conversion, and thermal transport in nanostructures

    Science.gov (United States)

    Maurer, Leon; Knezevic, Irena

    We study the effects of phonon mode conversion and Rayleigh (surface) waves on thermal transport in nanostructures. We present a technique to calculate thermal conductivity in the elastic-solid approximation: a finite-difference time-domain (FDTD) solution of the elastic or scalar wave equations combined with the Green-Kubo formula. The technique is similar to an equilibrium molecular dynamics simulation, captures phonon wave behavior, and scales well to nanostructures that are too large to simulate with many other techniques. By imposing fixed or free boundary conditions, we can selectively turn off mode conversion and Rayleigh waves to study their effects. In the example case of graphenelike nanoribbons with rough edges, we find that mode conversion among bulk modes has little effect on thermal transport, but that conversion between bulk and Rayleigh waves can significantly reduce thermal conductivity. With increasing surface disorder, Rayleigh waves readily become trapped by the disorder and draw energy away from the propagating bulk modes, which lowers thermal conductivity. We discuss the implications on the accuracy of popular phonon-surface scattering models that stem from scalar wave equations and cannot capture mode conversion to Rayleigh waves.

  5. What Supergranule Flow Models Tell Us About the Sun's Surface Shear Layer and Magnetic Flux Transport

    Science.gov (United States)

    Hathaway, David

    2011-01-01

    Models of the photospheric flows due to supergranulation are generated using an evolving spectrum of vector spherical harmonics up to spherical harmonic wavenumber l1500. Doppler velocity data generated from these models are compared to direct Doppler observations from SOHO/MDI and SDO/HMI. The models are adjusted to match the observed spatial power spectrum as well as the wavenumber dependence of the cell lifetimes, differential rotation velocities, meridional flow velocities, and relative strength of radial vs. horizontal flows. The equatorial rotation rate as a function of wavelength matches the rotation rate as a function of depth as determined by global helioseismology. This leads to the conclusions that the cellular structures are anchored at depths equal to their widths, that the surface shear layer extends to at least 70 degrees latitude, and that the poleward meridional flow decreases in amplitude and reverses direction at the base of the surface shear layer (approx.35 Mm below the surface). Using the modeled flows to passively transport magnetic flux indicates that the observed differential rotation and meridional flow of the magnetic elements are directly related to the differential rotation and meridional flow of the convective pattern itself. The magnetic elements are transported by the evolving boundaries of the supergranule pattern (where the convective flows converge) and are unaffected by the weaker flows associated with the differential rotation or meridional flow of the photospheric plasma.

  6. Research of photolithography technology based on surface plasmon

    Institute of Scientific and Technical Information of China (English)

    Li Hai-Hua; Chen Jian; Wang Qing-Kang

    2010-01-01

    This paper demonstrates a new process of the photolithography technology,used to fabricate simply fine patterns,by employing surface plasmon character.The sub-wavelength periodic silica structures with uniform silver film are used as the exposure mask.According to the traditional semiconductor process,the grating structures are fabricated at exposing wavelength of 436 nm.At the same time,it provides additional and quantitative support of this technique based on the finite-difference time-domain method.The results of the research show that surface plasmon characteristics of metals can be used to increase the optical field energy distribution differences through the silica structures with silver film,which directly impact on the exposure of following photosensitive layer in different regions.

  7. Rainfall intensity and phosphorus source effects on phosphorus transport in surface runoff from soil trays.

    Science.gov (United States)

    Shigaki, Francirose; Sharpley, Andrew; Prochnow, Luis Ignacio

    2007-02-01

    Phosphorus runoff from agricultural fields amended with mineral fertilizers and manures has been linked to freshwater eutrophication. A rainfall simulation study was conducted to evaluate the effects of different rainfall intensities and P sources differing in water soluble P (WSP) concentration on P transport in runoff from soil trays packed with a Berks loam and grassed with annual ryegrass (Lolium multiflorum Lam.). Triple superphosphate (TSP; 79% WSP), low-grade super single phosphate (LGSSP; 50% WSP), North Carolina rock phosphate (NCRP; 0.5% WSP) and swine manure (SM; 70% WSP), were broadcast (100 kg total P ha-1) and rainfall applied at 25, 50 and 75 mm h-1 1, 7, 21, and 56 days after P source application. The concentration of dissolved reactive (DRP), particulate (PP), and total P (TP) was significantly (Prunoff with a rainfall intensity of 75 than 25 mm h-1 for all P sources. Further, runoff DRP increased as P source WSP increased, with runoff from a 50 mm h-1 rain 1 day after source application having a DRP concentration of 0.25 mg L-1 for NCRP and 28.21 mg L-1 for TSP. In contrast, the proportion of runoff TP as PP was greater with low (39% PP for NCRP) than high WSP sources (4% PP for TSP) averaged for all rainfall intensities. The increased PP transport is attributed to the detachment and transport of undissolved P source particles during runoff. These results show that P source water solubility and rainfall intensity can influence P transport in runoff, which is important in evaluating the long-term risks of P source application on P transport in surface runoff.

  8. Ecological, Social and Economic Evaluation of Transport Scenarios: An Integral Approach. A Phd research programme

    NARCIS (Netherlands)

    Geurs KT; LAE

    2000-01-01

    This report describes a research programme for the development of a methodology for the integral assessment of ecological, economic and social impacts of transport scenarios. The following research activities are planned: (1) a literature study on theories and conceptual models, explaining the funct

  9. Ecological, Social and Economic Evaluation of Transport Scenarios: An Integral Approach. A Phd research programme

    NARCIS (Netherlands)

    Geurs KT; LAE

    2000-01-01

    This report describes a research programme for the development of a methodology for the integral assessment of ecological, economic and social impacts of transport scenarios. The following research activities are planned: (1) a literature study on theories and conceptual models, explaining the funct

  10. Japanese perspectives and research on packaging, transport and storage of spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Saegusa, T.; Ito, C.; Yamakawa, H.; Shirai, K. [Central Research Inst. of Electric Power Industry (CRIEPI), Abiko (Japan)

    2004-07-01

    The Japanese policy on spent fuel is reprocessing. Until, reprocessed, spent fuel shall be stored properly. This paper overviews current status of transport and storage of spent fuel with related research in Japan. The research was partly carried out under a contract of Ministry of Economy, Trade and Industry of the Japanese government.

  11. Coupling of morphology to surface transport in ion-beam-irradiated surfaces: normal incidence and rotating targets

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Garcia, Javier [Grupo Interdisciplinar de Sistemas Complejos (GISC) and School of Mathematical Sciences and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4 (Ireland); Cuerno, Rodolfo [Departamento de Matematicas and GISC, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes (Spain); Castro, Mario [GISC and Grupo de Dinamica No Lineal (DNL), Escuela Tecnica Superior de IngenierIa (ICAI), Universidad Pontificia Comillas de Madrid, E-28015 Madrid (Spain)], E-mail: javiermunozgarcia@gmail.com, E-mail: cuerno@math.uc3m.es, E-mail: mariocastro73@gmail.com

    2009-06-03

    Continuum models have proved their applicability to describe nanopatterns produced by ion-beam sputtering of amorphous or amorphizable targets at low and medium energies. Here we pursue the recently introduced 'hydrodynamic approach' in the cases of bombardment at normal incidence, or of oblique incidence onto rotating targets, known to lead to self-organized arrangements of nanodots. Our approach stresses the dynamical roles of material (defect) transport at the target surface and of local redeposition. By applying results previously derived for arbitrary angles of incidence, we derive effective evolution equations for these geometries of incidence, which are then numerically studied. Moreover, we show that within our model these equations are identical (albeit with different coefficients) in both cases, provided surface tension is isotropic in the target. We thus account for the common dynamics for both types of incidence conditions, namely formation of dots with short-range order and long-wavelength disorder, and an intermediate coarsening of dot features that improves the local order of the patterns. We provide for the first time approximate analytical predictions for the dependence of stationary dot features (amplitude and wavelength) on phenomenological parameters, that improve upon previous linear estimates. Finally, our theoretical results are discussed in terms of experimental data.

  12. Research on Evaluation of resource allocation efficiency of transportation system based on DEA

    Science.gov (United States)

    Zhang, Zhehui; Du, Linan

    2017-06-01

    In this paper, we select the time series data onto 1985-2015 years, construct the land (shoreline) resources, capital and labor as inputs. The index system of the output is freight volume and passenger volume, we use Quantitative analysis based on DEA method evaluated the resource allocation efficiency of railway, highway, water transport and civil aviation in China. Research shows that the resource allocation efficiency of various modes of transport has obvious difference, and the impact on scale efficiency is more significant. The most important two ways to optimize the allocation of resources to improve the efficiency of the combination of various modes of transport is promoting the co-ordination of various modes of transport and constructing integrated transportation system.

  13. A charge transport study in diamond, surface passivated by high-k dielectric oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kovi, Kiran Kumar, E-mail: KiranKumar.Kovi@angstrom.uu.se; Majdi, Saman; Gabrysch, Markus; Isberg, Jan [Division for Electricity, Department of Engineering Sciences, Box 534, Uppsala University, Uppsala SE-751 21 (Sweden)

    2014-11-17

    The recent progress in the growth of high-quality single-crystalline diamond films has sparked interest in the realization of efficient diamond power electronic devices. However, finding a suitable passivation is essential to improve the reliability and electrical performance of devices. In the current work, high-k dielectric materials such as aluminum oxide and hafnium oxide were deposited by atomic layer deposition on intrinsic diamond as a surface passivation layer. The hole transport properties in the diamond films were evaluated and compared to unpassivated films using the lateral time-of-flight technique. An enhancement of the near surface hole mobility in diamond films of up to 27% is observed when using aluminum oxide passivation.

  14. A Controlled Field Pilot for Testing Near Surface CO2 Detection Techniques and Transport Models

    Science.gov (United States)

    Spangler, L. H.; Dobeck, L.

    2007-12-01

    A field facility has been developed to allow controlled studies of near surface CO2transport and detection technologies. The key component of the facility is a shallow horizontal, well slotted over 70m of its length and divided into seven zones via packers with mass flow control in each individual zone. The scale and fluxes were designed to address large scale CO2 storage projects and desired retention rates for those projects and those design parameters will be discussed. A wide variety of detection techniques were deployed by collaborators from Los Alamos National Lab, Lawrence Berkeley National Lab, the National Energy Technology Lab, Pacific Northwest National Lab, Lawrence Livermore National Lab and West Virginia University. Techniques included eddy covariance, soil gas measurements, hyperspectral imaging for plant stress detection, differential absorption LIDAR (both free space atmospheric and below surface soil gas), tracer studies, water sampling, stable isotope studies, and soil flux chambers. An overview of these results will be presented.

  15. Observed and modeled surface Lagrangian transport between coastal regions in the Adriatic Sea with implications for marine protected areas

    Science.gov (United States)

    Carlson, Daniel F.; Griffa, Annalisa; Zambianchi, Enrico; Suaria, Giuseppe; Corgnati, Lorenzo; Magaldi, Marcello G.; Poulain, Pierre-Marie; Russo, Aniello; Bellomo, Lucio; Mantovani, Carlo; Celentano, Paolo; Molcard, Anne; Borghini, Mireno

    2016-04-01

    Surface drifters and virtual particles are used to investigate transport between seven coastal regions in the central and southern Adriatic Sea to estimate the degree to which these regions function as a network. Alongshore coastal currents and cyclonic gyres are the primary circulation features that connected regions in the Adriatic Sea. The historical drifter observations span 25 years and, thus, provide estimates of transport between regions realized by the mean surface circulation. The virtual particle trajectories and a dedicated drifter experiment show that southeasterly Sirocco winds can drive eastward cross-Adriatic transport from the Italian coast near the Gargano Promontory to the Dalmatian Islands in Croatia. Southeasterly winds disrupt alongshore transport on the west coast. Northwesterly Mistral winds enhanced east-to-west transport and resulted in stronger southeastward coastal currents in the western Adriatic current (WAC) and export to the northern Ionian Sea. The central Italian regions showed strong connections from north to south, likely realized by alongshore transport in the WAC. Alongshore, downstream transport was weaker on the east coast, likely due to the more complex topography introduced by the Dalmatian Islands of Croatia. Cross-Adriatic connection percentages were higher for east-to-west transport. Cross-Adriatic transport, in general, occurred via the cyclonic sub-gyres, with westward (eastward) transport observed in the northern (southern) arms of the central and southern gyres.

  16. Savannah River Laboratory environmental transport and effects research. Annual report, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, T.V. (comp.)

    1979-11-01

    Research in the environmental sciences by the Savannah River Laboratory during 1978 is described in 43 articles. These articles are in the fields of terrestrial ecology, geologic studies, aquatic transport, aquatic ecology, atmospheric transport, emergency response, computer methods development, ocean program, and fuel cycle program. Thirty-seven of the articles were abstracted individually for ERA/EDB; those in scope were also included in INIS.

  17. Journal of Airline and Airport Management: Taking off on an exciting journey into Air Transport Research

    Directory of Open Access Journals (Sweden)

    David Gonzalez-Prieto

    2011-11-01

    Full Text Available We are pleased to introduce this first and inaugural issue of the first volume of the Journal of Airline and Airport Management (JAIRM. JAIRM is an international journal that proposes and fosters discussion on the theory and application in all areas of air transport, including (but not limited to air transport and globalization, airline and airport management. We are interested in issues related to production, logistics, operations, marketing, policy and regulation, information systems, project management, quality, as well as regional development, economics, organizational behaviour, finance and accounting in air transport research.

  18. Interactions between bacteria and solid surfaces in relation to bacterial transport in porous media

    NARCIS (Netherlands)

    Rijnaarts, H.H.M.

    1994-01-01

    Interactions between bacteria and solid surfaces strongly influence the behaviour of bacteria in natural and engineered ecosystems. Many biofilm reactors and terrestrial environments are porous media. The purpose of the research presented in this thesis is to gain a better insight into the

  19. Interactions between bacteria and solid surfaces in relation to bacterial transport in porous media.

    NARCIS (Netherlands)

    Rijnaarts, H.H.M.

    1994-01-01

    Interactions between bacteria and solid surfaces strongly influence the behaviour of bacteria in natural and engineered ecosystems. Many biofilm reactors and terrestrial environments are porous media. The purpose of the research presented in this thesis is to gain a better insight into the basic mec

  20. Intelligent Transportation Systems Research Data Exchange - National Center for Atmospheric Research 2009 - RSE Parsed Processed Data

    Data.gov (United States)

    Department of Transportation — See the Vehicle Infrastructure Initiative Proof of Concept data environment for a description of the Michigan Test Bed and the data collected there in 2008. In April...

  1. Bulk and surface electron transport in topological insulator candidate YbB{sub 6-δ}

    Energy Technology Data Exchange (ETDEWEB)

    Glushkov, Vladimir V.; Demishev, Sergey V.; Sluchanko, Nikolay E. [Prokhorov General Physics Institute of RAS, Vavilov str. 38, 119991, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Institutskii per. 9, 141700, Dolgoprudny, Moscow Region (Russian Federation); Bozhko, Alexey D.; Bogach, Alexey V.; Semeno, Alexey V.; Voronov, Valeriy V. [Prokhorov General Physics Institute of RAS, Vavilov str. 38, 119991, Moscow (Russian Federation); Dukhnenko, Anatoliy V.; Filipov, Volodimir B.; Shitsevalova, Natalya Yu. [Frantsevich Institute for Problems of Materials Science NAS, Krzhyzhanovsky str. 3, 03680, Kiev (Ukraine); Kondrin, Mikhail V. [Vereshchagin Institute of High Pressure Physics of RAS, 142190, Troitsk, Moscow (Russian Federation); Kuznetsov, Alexey V.; Sannikov, Ilia I. [National Research Nuclear University ' ' MEPhI' ' , Kashirskoe Shosse 31, 115409, Moscow (Russian Federation)

    2016-04-15

    We report the study of transport and magnetic properties of the YbB{sub 6-δ}single crystals grown by inductive zone melting. A strong disparity in the low temperature resistivity, Seebeck and Hall coefficients is established for the samples with the different level of boron deficiency. The effective parameters of the charge transport in YbB{sub 6-δ} are shown to depend on the concentration of intrinsic defects, which is estimated to range from 0.09% to 0.6%. The pronounced variation of Hall mobility μ{sub H} found for bulk holes is induced by the decrease of transport relaxation time from τ ∼ 7.7 fs for YbB{sub 5.994} to τ ∼ 2.2 fs for YbB{sub 5.96}. An extra contribution to conductivity from electrons with μ{sub H}∼ -1000 cm{sup 2} V{sup -1} s{sup -1} and the very low concentration n /n{sub Yb}∼ 10{sup -6} discovered below 20 K for all the single crystals under investigation is suggested to arise from the surface electron states appeared in the inversion layer due to the band bending. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Surface transport and stable trapping of particles and cells by an optical waveguide loop.

    Science.gov (United States)

    Hellesø, Olav Gaute; Løvhaugen, Pål; Subramanian, Ananth Z; Wilkinson, James S; Ahluwalia, Balpreet Singh

    2012-09-21

    Waveguide trapping has emerged as a useful technique for parallel and planar transport of particles and biological cells and can be integrated with lab-on-a-chip applications. However, particles trapped on waveguides are continuously propelled forward along the surface of the waveguide. This limits the practical usability of the waveguide trapping technique with other functions (e.g. analysis, imaging) that require particles to be stationary during diagnosis. In this paper, an optical waveguide loop with an intentional gap at the centre is proposed to hold propelled particles and cells. The waveguide acts as a conveyor belt to transport and deliver the particles/cells towards the gap. At the gap, the diverging light fields hold the particles at a fixed position. The proposed waveguide design is numerically studied and experimentally implemented. The optical forces on the particle at the gap are calculated using the finite element method. Experimentally, the method is used to transport and trap micro-particles and red blood cells at the gap with varying separations. The waveguides are only 180 nm thick and thus could be integrated with other functions on the chip, e.g. microfluidics or optical detection, to make an on-chip system for single cell analysis and to study the interaction between cells.

  3. Methodologies for Removing/Desorbing and Transporting Particles from Surfaces to Instrumentation

    Science.gov (United States)

    Miller, Carla J.; Cespedes, Ernesto R.

    2012-12-01

    Explosive trace detection (ETD) continues to be a key technology supporting the fight against terrorist bombing threats. Very selective and sensitive ETD instruments have been developed to detect explosive threats concealed on personnel, in vehicles, in luggage, and in cargo containers, as well as for forensic analysis (e.g. post blast inspection, bomb-maker identification, etc.) in a broad range of homeland security, law enforcement, and military applications. A number of recent studies have highlighted the fact that significant improvements in ETD systems' capabilities will be achieved, not by increasing the selectivity/sensitivity of the sensors, but by improved techniques for particle/vapor sampling, pre-concentration, and transport to the sensors. This review article represents a compilation of studies focused on characterizing the adhesive properties of explosive particles, the methodologies for removing/desorbing these particles from a range of surfaces, and approaches for transporting them to the instrument. The objectives of this review are to summarize fundamental work in explosive particle characterization, to describe experimental work performed in harvesting and transport of these particles, and to highlight those approaches that indicate high potential for improving ETD capabilities.

  4. Towards the future: The promise of intermodal and multimodal transportation systems. Research report

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.E.; Easley, R.B.; Fowler, T.M.; Gabler, W.L.; Govind, S.

    1995-02-01

    Issues relating to intermodal and multimodal transportation systems are introduced and defined. Intermodal and multimodal transportation solutions are assessed within the framework of legislative efforts such as Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), Clean Air Act Amendments of 1990 (CAAA), and North American Free Trade Agreement (NAFTA). Federal involvement in state intermodal transportation systems, and state responses to the growing intermodal and multimodal trends are also reviewed. The roles and responsibilities of the Metropolitan Planning Organizations (MPO) in the post-ISTEA world is examined and the impacts of legislative mandates considered. As a case study, the workings of the Houston MPO are examined. Private sector intermodal and multimodal involvement is addressed, including issues in management, regulatory, financial, economical, environmental, and even physical constraints. Effects of regulation on private sector intermodalism are discussed, as are case studies in partnering and management.

  5. Influence of near-surface blisters on deuterium transport in tungsten

    Science.gov (United States)

    Bauer, J.; Schwarz-Selinger, T.; Schmid, K.; Balden, M.; Manhard, A.; von Toussaint, U.

    2017-08-01

    The effect of near-surface blisters on deuterium transport in tungsten is studied by means of nuclear reaction analysis (NRA) and scanning electron microscopy (SEM). Gentle deuterium plasma loading of different durations and subsequent NRA depth profiling is performed in heavily pre-blistered and unblistered areas on self-damaged tungsten samples. Comparison of the deuterium depth profiles reveals a considerable reduction of the deuterium transport into the bulk due to the presence of near-surface blisters. SEM and NRA results identify the enhanced re-emission of deuterium from the sample due to open blisters as the underlying mechanism, which reduces the deuterium flux into the bulk. Based on a simple analytical hydrogen retention model, the re-emitted deuterium flux by open blisters is determined to be 80% of the implanted deuterium flux in the present conducted experiment. In addition, the deuterium flux into the bulk is reduced by 60% compared to the unblistered case. Hence the presence of blisters is not a general disadvantage in the context of retention, but can be beneficial in slowing down the build up of a certain hydrogen inventory and in reducing the permeation flux.

  6. Oceanic transport of surface meltwater from the southern Greenland ice sheet

    Science.gov (United States)

    Luo, Hao; Castelao, Renato M.; Rennermalm, Asa K.; Tedesco, Marco; Bracco, Annalisa; Yager, Patricia L.; Mote, Thomas L.

    2016-07-01

    The Greenland ice sheet has undergone accelerating mass losses during recent decades. Freshwater runoff from ice melt can influence fjord circulation and dynamics and the delivery of bioavailable micronutrients to the ocean. It can also have climate implications, because stratification in the adjacent Labrador Sea may influence deep convection and the strength of the Atlantic meridional overturning circulation. Yet, the fate of the meltwater in the ocean remains unclear. Here, we use a high-resolution ocean model to show that only 1-15% of the surface meltwater runoff originating from southwest Greenland is transported westwards. In contrast, up to 50-60% of the meltwater runoff originating from southeast Greenland is transported westwards into the northern Labrador Sea, leading to significant salinity and stratification anomalies far from the coast. Doubling meltwater runoff, as predicted in future climate scenarios, results in a more-than-double increase in anomalies offshore that persists further into the winter. Interannual variability in offshore export of meltwater is tightly related to variability in wind forcing. The new insight that meltwaters originating from the west and east coasts have different fates indicates that future changes in mass loss rates and surface runoff will probably impact the ocean differently, depending on their Greenland origins.

  7. ATP-binding cassette transporter controls leaf surface secretion of anticancer drug components in Catharanthus roseus.

    Science.gov (United States)

    Yu, Fang; De Luca, Vincenzo

    2013-09-24

    The Madagascar periwinkle (Catharanthus roseus) is highly specialized for the biosynthesis of many different monoterpenoid indole alkaloids (MIAs), many of which have powerful biological activities. Such MIAs include the commercially important chemotherapy drugs vinblastine, vincristine, and other synthetic derivatives that are derived from the coupling of catharanthine and vindoline. However, previous studies have shown that biosynthesis of these MIAs involves extensive movement of metabolites between specialized internal leaf cells and the leaf epidermis that require the involvement of unknown secretory processes for mobilizing catharanthine to the leaf surface and vindoline to internal leaf cells. Spatial separation of vindoline and catharanthine provides a clear explanation for the low levels of dimers that accumulate in intact plants. The present work describes the molecular cloning and functional identification of a unique catharanthine transporter (CrTPT2) that is expressed predominantly in the epidermis of young leaves. CrTPT2 gene expression is activated by treatment with catharanthine, and its in planta silencing redistributes catharanthine to increase the levels of catharanthine-vindoline drug dimers in the leaves. Phylogenetic analysis shows that CrTPT2 is closely related to a key transporter involved in cuticle assembly in plants and that may be unique to MIA-producing plant species, where it mediates secretion of alkaloids to the plant surface.

  8. Oceanic Transport of Surface Meltwater from the Southern Greenland Ice Sheet

    Science.gov (United States)

    Luo, Hao; Castelao, Renato M.; Rennermalm, Asa K.; Tedesco, Marco; Bracco, Annalisa; Yager, Patricia L.; Mote, Thomas L.

    2016-01-01

    The Greenland ice sheet has undergone accelerating mass losses during recent decades. Freshwater runoff from ice melt can influence fjord circulation and dynamic1 and the delivery of bioavailable micronutrients to the ocean. It can also have climate implications, because stratification in the adjacent Labrador Sea may influence deep convection and the strength of the Atlantic meridional overturning circulation. Yet, the fate of the meltwater in the ocean remains unclear. Here, we use a high-resolution ocean model to show that only 1-15% of the surface meltwater runoff originating from southwest Greenland is transported westwards. In contrast, up to 50-60% of the meltwater runoff originating from southeast Greenland is transported westwards into the northern Labrador Sea, leading to significant salinity and stratification anomalies far from the coast. Doubling meltwater runoff, as predicted in future climate scenarios, results in a more-than-double increase in anomalies offshore that persists further into the winter. Interannual variability in offshore export of meltwater is tightly related to variability in wind forcing. The new insight that meltwaters originating from the west and east coasts have different fates indicates that future changes in mass loss rates and surface runoff will probably impact the ocean differently, depending on their Greenland origins.

  9. Factors contributing to the off-target transport of pyrethroid insecticides from urban surfaces.

    Science.gov (United States)

    Jorgenson, Brant C; Wissel-Tyson, Christopher; Young, Thomas M

    2012-08-01

    Pyrethroid insecticides used in urban and suburban contexts have been found in urban creek sediments and associated with toxicity in aquatic bioassays. The objectives of this study were to evaluate the main factors contributing to the off-target transport of pyrethroid insecticides from surfaces typical of residential landscapes. Controlled rainfall simulations over concrete, bare soil, and turf plots treated individually with pyrethroid insecticides in a suspension concentrate, an emulsifiable concentrate, or a granule formulation were conducted at different rainfall intensities and different product set-time intervals. Pyrethroid mass washoff varied by several orders of magnitude between experimental treatments. Suspension concentrate product application to concrete yielded significantly greater washoff than any other treatment; granule product application to turf yielded the least washoff. Fractional losses at 10 L of runoff ranged from 25.9 to 0.011% of pyrethroid mass applied, and 10 L nominal mass losses ranged from 3970 to 0.18 μg. Mass washoff depended principally on formulation and surface type combination and, to a lesser degree, on set-time interval and rainfall intensity. Treatment effects were analyzed by ANOVA on main factors of formulation, surface type, and set time. Factor effects were not purely additive; a significant interaction between formulation and surface type was noted.

  10. The Signature Sequence Region of the Human Drug Transporter Organic Anion Transporting Polypeptide 1B1 Is Important for Protein Surface Expression

    Directory of Open Access Journals (Sweden)

    Jennina Taylor-Wells

    2014-01-01

    Full Text Available The organic anion transporting polypeptides (OATPs encompass a family of membrane transport proteins responsible for the uptake of xenobiotic compounds. Human organic anion transporting polypeptide 1B1 (OATP1B1 mediates the uptake of clinically relevant compounds such as statins and chemotherapeutic agents into hepatocytes, playing an important role in drug delivery and detoxification. The OATPs have a putative 12-transmembrane domain topology and a highly conserved signature sequence (human OATP1B1: DSRWVGAWWLNFL, spanning the extracellular loop 3/TM6 boundary. The presence of three conserved tryptophan residues at the TM interface suggests a structural role for the sequence. This was investigated by site-directed mutagenesis of selected amino acids within the sequence D251E, W254F, W258/259F, and N261A. Transport was measured using the substrate estrone-3-sulfate and surface expression detected by luminometry and confocal microscopy, facilitated by an extracellular FLAG epitope. Uptake of estrone-3-sulfate and the surface expression of D251E, W254F, and W258/259F were both significantly reduced from the wild type OATP1B1-FLAG in transfected HEK293T cells. Confocal microscopy revealed that protein was produced but was retained intracellularly. The uptake and expression of N261A were not significantly different. The reduction in surface expression and intracellular protein retention indicates a structural and/or membrane localization role for these signature sequence residues in the human drug transporter OATP1B1.

  11. The Signature Sequence Region of the Human Drug Transporter Organic Anion Transporting Polypeptide 1B1 Is Important for Protein Surface Expression.

    Science.gov (United States)

    Taylor-Wells, Jennina; Meredith, David

    2014-01-01

    The organic anion transporting polypeptides (OATPs) encompass a family of membrane transport proteins responsible for the uptake of xenobiotic compounds. Human organic anion transporting polypeptide 1B1 (OATP1B1) mediates the uptake of clinically relevant compounds such as statins and chemotherapeutic agents into hepatocytes, playing an important role in drug delivery and detoxification. The OATPs have a putative 12-transmembrane domain topology and a highly conserved signature sequence (human OATP1B1: DSRWVGAWWLNFL), spanning the extracellular loop 3/TM6 boundary. The presence of three conserved tryptophan residues at the TM interface suggests a structural role for the sequence. This was investigated by site-directed mutagenesis of selected amino acids within the sequence D251E, W254F, W258/259F, and N261A. Transport was measured using the substrate estrone-3-sulfate and surface expression detected by luminometry and confocal microscopy, facilitated by an extracellular FLAG epitope. Uptake of estrone-3-sulfate and the surface expression of D251E, W254F, and W258/259F were both significantly reduced from the wild type OATP1B1-FLAG in transfected HEK293T cells. Confocal microscopy revealed that protein was produced but was retained intracellularly. The uptake and expression of N261A were not significantly different. The reduction in surface expression and intracellular protein retention indicates a structural and/or membrane localization role for these signature sequence residues in the human drug transporter OATP1B1.

  12. No-Loss Transportation of Water Droplets by Patterning a Desired Hydrophobic Path on a Superhydrophobic Surface.

    Science.gov (United States)

    Hu, Haibao; Yu, Sixiao; Song, Dong

    2016-07-26

    The directional transportation of droplets on solid surfaces is essential in a wide range of engineering applications. It is convenient to guide liquid droplets in a given direction by utilizing the gradient of wettability, by which the binding forces can be produced. In contrast to the mass-loss transportation of a droplet moving along hydrophilic paths on a horizontal superhydrophobic surface, we present no-loss transportation by fabricating a hydrophobic path on the same surface under tangential wind. In experimental exploration and theoretical analysis, the conditions of no-loss transportation of a droplet are mainly considered. We demonstrate that the lower (or upper) critical wind velocity, under which the droplet starts on the path (or is derailed from the path), is determined by the width of the path, the length of the contact area in the direction parallel to the path, the drift angle between the path and the wind direction, and the surface wettability of the pattern. Meanwhile, the no-loss transportation of water droplets along the desired path zigzagging on a superhydrophobic surface can be achieved steadily under appropriate conditions. We anticipate that such robust no-loss transportation will find an extensive range of applications.

  13. A Study of Transport and Impact Strength of Fukushima Nuclear Pollutants in the North Pacific Surface

    Institute of Scientific and Technical Information of China (English)

    FU Hongli; LI Wei; ZHANG Xuefeng; HAN Guijun; WANG Xidong; WU Xinrong; ZHANG Lianxin

    2014-01-01

    Based on the statistics of surface drifter data of 1979-2011 and the simulation of nuclear pollutant particulate move-ments simulated using high quality ocean reanalysis surface current dataset, the transport pathways and impact strength of Fuku-shima nuclear pollutants in the North Pacific have been estimated. The particulates are used to increase the sampling size and en-hance the representativeness of statistical results. The trajectories of the drifters and particulates are first examined to identify typical drifting pathways. The results show that there are three types of transport paths for nuclear pollutants at the surface: 1) most pollutant particles move eastward and are carried by the Kuroshio and Kuroshio-extension currents and reach the east side of the North Pacific after about 3.2-3.9 years;2) some particles travel with the subtropical circulation branch and reach the east coast of China after about 1.6 years according to one drifter trajectory and about 3.6 years according to particulate trajectories;3) a little of them travel with local, small scale circulations and reach the east coast of China after about 1.3-1.8 years. Based on the par-ticulates, the impact strength of nuclear pollutants at these time scales can be estimated according to the temporal variations of relative concentration combined with the radioactive decay rate. For example, Cesium-137, carried by the strong North Pacific current, mainly accumulates in the eastern North Pacific and its impact strength is 4%of the initial level at the originating Fuku-shima area after 4 years. Due to local eddies, Cesium-137 in the western North Pacific is 1%of the initial pollutant level after 1.5 years and continuously increases to 3%after 4 years. The vertical movement of radioactive pollutants is not taken into account in the present study, and the estimation accuracy would be improved by considering three-dimensional flows.

  14. Transport and fate of nitrate at the ground-water/surface-water interface

    Science.gov (United States)

    Puckett, L.J.; Zamora, C.; Essaid, H.; Wilson, J.T.; Johnson, H.M.; Brayton, M.J.; Vogel, J.R.

    2008-01-01

    Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data, were used to determine the processes controlling transport and fate of NO3- in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five points across the stream and in two to five separate transects. Residence times of water ranging from 0.28 to 34.7 d m-1 in the streambeds of N-rich watersheds played an important role in allowing denitrification to decrease NO3- concentrations. Where potential electron donors were limited and residence times were short, denitrification was limited. Consequently, in spite of reducing conditions at some sites, NO3- was transported into the stream. At two of the five study sites, NO3- in surface water infiltrated the streambeds and concentrations decreased, supporting current models that NO3- would be retained in N-rich streams. At the other three study sites, hydrogeologic controls limited or prevented infiltration of surface water into the streambed, and ground-water discharge contributed to NO 3- loads. Our results also show that in these low hydrologic-gradient systems, storm and other high-flow events can be important factors for increasing surface-water movement into streambeds. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  15. Surface runoff from manured cropping systems assessed by the paired-watershed method, part 1: P, N, and sediment transport

    Science.gov (United States)

    Transport of P, N, and sediment via runoff from crop fields can contribute to degradation of surface waters. We established a paired-watershed study in central Wisconsin to evaluate surface runoff losses of nutrients, sediment, and pathogens from different manure/crop/tillage management systems for ...

  16. Gender mainstreaming european transport research and policies. Building the knowledge base and mapping good practices

    Energy Technology Data Exchange (ETDEWEB)

    Roemer Christensen, H.; Poulsen, H.; Hjorth Oldrup, H.; Malthesen, T.; Hvidt Breengaard, M.; Holmen, M.

    2007-07-01

    This report documents that there are clear and persistent gender differences in travel patterns. Men consistently travel further than women, men are more likely to travel by car and women by public transport, and women's trips tend to be more local. Explanations to these differences are linked to unequal gendered relations in the household and labour market and urban structures as well as gender socialisation. This means that men and women make different uses of a shared system of transport. Transport is an overwhelmingly male-dominated sector. At the EU level, political committees in the transport sector as well as transport research and advisory boards have a marked gender imbalance with less than 15% female membership in most boards and none with equal representation. This also goes for transport-related committees at national levels. Yet with one notable exception: Sweden has a 50-50 balance in the National Transport Committee. Current gender mainstreaming initiatives in the transport sector relate to a wide range of issues: They relate to planning and policy, safety issues, gendering of technology as well as employment. The report substantiates that the implementation of equality programmes, and not their formulation makes up the biggest challenge. One programme does not solve all problems, but opens up new avenues for initiatives and intervention. Gender is a central stratifying factor in transport use at all levels. In order to provide a more complete picture of gender differences, and in order to qualify EU goals of combating multi-level inequalities, there is a need to link gender with the broader axes of inequalities, namely ethnicity, sexuality, age and handicap in future studies of transport and mobility. (au)

  17. Optimization of city transportation of cargoes with use of system researches in the field of logistics

    Directory of Open Access Journals (Sweden)

    Олександр Павлович Кіркін

    2015-03-01

    Full Text Available In market working conditions, the enterprises need to maintain the competitiveness constantly. It is reached due to increase of standards of customer service and application of the latest technologies of management and production, including logistics. Over time there were following kinds of logistics: transport, warehouse, supply, production, etc. Thus, there is some parallel methodological development in the field of logistics and creation of logistic chains and systems at various stages of life cycle of goods. Thus, for city transportations, except high requirements to ecology and the impacts on the person inherent quick search of administrative decisions on effective customer service for the minimum time is. The warehouse logistics is an intermediate link between economic models by definition of stocks and parties of purchase, and transport operations which these indicators influence. Thus, system researches in the field of warehouse and transport logistic allow to coordinate transport and warehouse operations in uniform indicators, and also to expand methods of transport logistics. Planning and management of transport operations with the solution of problems of the target conflict can be used only for continuous transport sizes. First of all it is connected with impossibility of accumulation of transport works. It is necessary to notice feature of the solution of problems of the target conflict which can carry as the end result, and it can be presented by function, including function of distribution of a random variable. Therefore, the solution of a task can be used in imitating modeling. For transport operations it is necessary to consider two cases: the maximum intensity of service can't be increased and possibility of accumulation of intensity of service at the expense of additional resources

  18. High resolution imaging of vadose zone transport using surface and crosswell ground penetrating radar methods

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kenneth H.; Kowalsky, Mike B.; Peterson, John E.

    2002-11-05

    To effectively clean up many contaminated sites there is a need for information on heterogeneities at scales ranging from one centimeter to tens of meters, as these features can alter contaminant transport significantly. At the Department of Energy's Hanford, Washington site heterogeneities of interest can range from localized phenomena such as silt or gravel lenses, fractures, clastic dikes, to large-scale lithologic discontinuities. In the vadose zone it is critical to understand the parameters controlling flow. These features have been suspected of leading to funneling and fingering, additional physical mechanisms that could alter and possibly accelerate the transport of contaminants to underlying groundwater. For example, it has been observed from the studies to date that over relatively short distances there are heterogeneities in the physical structure of the porous medium and structural differences between repacked soil cores and the field site from which the materials initially came (Raymond and Shdo, 1966). Analysis of cores taken from the vadose zone (i.e., soil surface to water table) has been useful in identifying localized zones of contamination. Unfortunately, these analyses are sparse (limited to a few boreholes) and extremely expensive. The high levels of radioactivity at many of the contaminated sites increase drilling and sample costs and analysis time. Cost of drilling and core analysis for the SX tank farm has exceeded $1M per borehole (50 meter deep) for sampling. The inability to track highly mobile species through the vadose zone highlights an important need: the need for methods to describe the complete vadose zone plume and to determine processes controlling accelerated contamination of groundwater at Hanford. A combination of surface and crosswell (i.e. borehole) geophysical measurements is one means to provide this information. The main questions addressed with the radar methods in this study are: (1) What parts of the vadose zone

  19. Onsager heat of transport of carbon dioxide at the surface of aqueous ammonia: The remarkable effect of carbamate formation

    Science.gov (United States)

    Packwood, Daniel M.; Phillips, Leon F.

    2010-11-01

    The Onsager heat of transport Q∗ has been measured for CO 2 at the surface of aqueous ammonia. The heat of transport incorporates the enthalpy of reaction of gaseous CO 2 with ammonia, adsorbed on the liquid surface, to form adsorbed ammonium carbamate, with the result that -Q∗ has the unusually large value of 180 kJ mol -1. Measurement of Q∗ for transfer of a reactive species through a surfactant monolayer is proposed as a new method of studying reactions at liquid and quasi-liquid surfaces.

  20. Surface-modified silica colloidal crystals: nanoporous films and membranes with controlled ionic and molecular transport.

    Science.gov (United States)

    Zharov, Ilya; Khabibullin, Amir

    2014-02-18

    Nanoporous membranes are important for the study of the transport of small molecules and macromolecules through confined spaces and in applications ranging from separation of biomacromolecules and pharmaceuticals to sensing and controlled release of drugs. For many of these applications, chemists need to gate the ionic and molecular flux through the nanopores, which in turn depends on the ability to control the nanopore geometry and surface chemistry. Most commonly used nanoporous membrane materials are based on polymers. However, the nanostructure of polymeric membranes is not well-defined, and their surface is hard to modify. Inorganic nanoporous materials are attractive alternatives for polymers in the preparation of nanoporous membranes. In this Account, we describe the preparation and surface modification of inorganic nanoporous films and membranes self-assembled from silica colloidal spheres. These spheres form colloidal crystals with close-packed face centered cubic lattices upon vertical deposition from colloidal solutions. Silica colloidal crystals contain ordered arrays of interconnected three dimensional voids, which function as nanopores. We can prepare silica colloidal crystals as supported thin films on various flat solid surfaces or obtain free-standing silica colloidal membranes by sintering the colloidal crystals above 1000 °C. Unmodified silica colloidal membranes are capable of size-selective separation of macromolecules, and we can surface-modify them in a well-defined and controlled manner with small molecules and polymers. For the surface modification with small molecules, we use silanol chemistry. We grow polymer brushes with narrow molecular weight distribution and controlled length on the colloidal nanopore surface using atom transfer radical polymerization or ring-opening polymerization. We can control the flux in the resulting surface-modified nanoporous films and membranes by pH and ionic strength, temperature, light, and small molecule

  1. Transport rectification in nanopores with outer membranes modified with surface charges and polyelectrolytes.

    Science.gov (United States)

    Tagliazucchi, Mario; Rabin, Yitzhak; Szleifer, Igal

    2013-10-22

    This work reports a comprehensive theoretical study of the transport-rectification properties of cylindrical nanopores with neutral inner walls and chemically modified outer membrane. The chemical species on the two outer sides of the membrane have charges of opposite sign and can be either surface-confined species (i.e., surface charges) or polyelectrolyte brushes. The advantage of this design over other types of rectifying nanopores is that it requires controlling the composition of the outer walls of the pore (which are easy to access) rather than the inner walls, thus simplifying the fabrication process. Ion-current rectification in nanopores with charged outer walls is ascribed to applied-potential-induced changes in the ionic concentration within the pore. The rectification efficiency is studied as a function of pore length, radius, surface charge and bulk electrolyte concentration. An analytical model is derived for the case of surface-confined charges that predicts the current-potential curves in very good agreement with the numerical calculations. Neutral nanopores with polyelectrolyte-modified outer walls have two distinct advantages compared to surface-charged systems: (i) they exhibit higher rectification factors due to the large charge density immobilized by the polyelectrolyte brushes, and (ii) the applied potential deforms the polyelectrolyte chains toward the oppositely charged electrode. This deformation brings the polyelectrolyte brushes into the pore in the low conductivity state and expels them from the pore in the high conductivity regime. Calculations of the potentials of mean-force suggest that the applied-field-induced conformational changes can be used to control the translocation of cargoes larger than ions, such as proteins and nanoparticles.

  2. Modeling Groundwater-Surface Water Interaction and Contaminant Transport of Chlorinated Solvent Contaminated Site

    Science.gov (United States)

    Yimer Ebrahim, Girma; Jonoski, Andreja; van Griensven, Ann; Dujardin, Juliette; Baetelaan, Okke; Bronders, Jan

    2010-05-01

    Chlorinated-solvent form one of the largest groups of environmental chemicals. Their use and misuse in industry have lead to a large entry of these chemicals into the environment, resulting in widespread dissemination and oftentimes environmental contamination. Chlorinated solvent contamination of groundwater resources has been widely reported. For instance, there has been much interest in the assessment of these contaminant levels and their evolutions with time in the groundwater body below the Vilvoorde-Machelen industrial area (Belgium). The long industrial history of the area has lead to complex patterns of pollution from multiple sources and the site has been polluted to the extent that individual plumes are not definable any more. Understanding of groundwater/surface water interaction is a critical component for determining the fate of contaminant both in streams and ground water due to the fact that groundwater and surface water are in continuous dynamic interaction in the hydrologic cycle. The interaction has practical consequences in the quantity and quality of water in either system in the sense that depletion and/or contamination of one of the system will eventually affect the other one. The transition zone between a stream and its adjacent aquifer referred to as the hyporheic zone plays a critical role in governing contaminant exchange and transformation during water exchange between the two water bodies. The hyporheic zone of Zenne River ( the main receptor ) is further complicated due to the fact that the river banks are artificially trained with sheet piles along its reach extending some 12 m below the surface. This study demonstrates the use of MODFLOW, a widely used modular three-dimensional block-centred finite difference, saturated flow model for simulating the flow and direction of movement of groundwater through aquifer and stream-aquifer interaction and the use of transport model RT3D, a three-dimensional multi-species reactive transport model

  3. Research on CO2 Quality Pipeline Transportation Based on Yanchang Oilfield CCUS

    Directory of Open Access Journals (Sweden)

    Yang Yongchao

    2017-01-01

    Full Text Available CO2 capture,utilization and storage (CCUS is now recognized as an important technology in the global scope of CO2 emission reduction, pipeline transportation is the main center to connect the capture point and the use storage point, the first issue to CO2 pipeline transportation is to solve CO2 source quality research. Yanchang Oilfield has the advantages of CCUS, its coal chemical capture of CO2 contains different impurities. In the CO2 pipeline transportation, the impurity content in CO2 is based on its end use and the actual situation of pipeline. The impurities will affect the efficiency of CO2-EOR, the choice of CO2 state equation, the changes of CO2 phase diagram and the capacity of pipeline transportation.

  4. New York state high-speed surface transportation study: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-01

    In 1990, New York State Governor Mario M. Cuomo created an interagency task force under the leadership of Lt. Governor Stan Lundine to investigate the potential of high speed ground transportation (HSGT) systems. Building on information from previous agency activities, including consultant efforts contracted by the New York State Energy Research and Development Authority (NYSERDA), the New York State Thruway Authority (NYSTA), and in-house analyses performed by New York State Department of Transportation (NYSDOT), the task force focused on the corridor between New York City and the Niagara Frontier. In December 1991, NYSERDA issued a contract for a study of high speed ground transportation options for New York State. The study`s objective was to assess potential rights-of-way, ridership, energy and environmental impacts, economic benefits, capital, operating, and maintenance costs, and financial viability of HSGT systems. This study builds upon and supplements previous and on-going HSGT activities conducted by the members of the interagency task force. These activities include: Maglev Technical and Economic Feasibility Study (NYSERDA); Maglev Demonstration Site Investigation (NYSTA); and New York/Massachusetts High Speed Ground Transportation Study (NYSDOT). This study is intended to verify and refine previous information and analyses and provide supplemental information and insights to be used in determining if additional investigation and activities involving HSGT are desirable for New York State. This study evaluates HSGT technologies capable of speeds significantly higher than those achieved with the present rail system. Three HSGT categories are used in this study: incremental rail improvement, very high-speed rail, and Maglev.

  5. Mass Transport in Surface Diffusion of van der Waals Bonded Systems: Boosted by Rotations?

    Science.gov (United States)

    Hedgeland, Holly; Sacchi, Marco; Singh, Pratap; McIntosh, Andrew J; Jardine, Andrew P; Alexandrowicz, Gil; Ward, David J; Jenkins, Stephen J; Allison, William; Ellis, John

    2016-12-01

    Mass transport at a surface is a key factor in heterogeneous catalysis. The rate is determined by excitation across a translational barrier and depends on the energy landscape and the coupling to the thermal bath of the surface. Here we use helium spin-echo spectroscopy to track the microscopic motion of benzene adsorbed on Cu(001) at low coverage (θ ∼ 0.07 ML). Specifically, our combined experimental and computational data determine both the absolute rate and mechanism of the molecular motion. The observed rate is significantly higher by a factor of 3.0 ± 0.1 than is possible in a conventional, point-particle model and can be understood only by including additional molecular (rotational) coordinates. We argue that the effect can be described as an entropic contribution that enhances the population of molecules in the transition state. The process is generally relevant to molecular systems and illustrates the importance of the pre-exponential factor alongside the activation barrier in studies of surface kinetics.

  6. Orf virus interferes with MHC class I surface expression by targeting vesicular transport and Golgi

    Directory of Open Access Journals (Sweden)

    Rohde Jörg

    2012-07-01

    Full Text Available Abstract Background The Orf virus (ORFV, a zoonotic Parapoxvirus, causes pustular skin lesions in small ruminants (goat and sheep. Intriguingly, ORFV can repeatedly infect its host, despite the induction of a specific immunity. These immune modulating and immune evading properties are still unexplained. Results Here, we describe that ORFV infection of permissive cells impairs the intracellular transport of MHC class I molecules (MHC I as a result of structural disruption and fragmentation of the Golgi apparatus. Depending on the duration of infection, we observed a pronounced co-localization of MHC I and COP-I vesicular structures as well as a reduction of MHC I surface expression of up to 50%. These subversion processes are associated with early ORFV gene expression and are accompanied by disturbed carbohydrate trimming of post-ER MHC I. The MHC I population remaining on the cell surface shows an extended half-life, an effect that might be partially controlled also by late ORFV genes. Conclusions The presented data demonstrate that ORFV down-regulates MHC I surface expression in infected cells by targeting the late vesicular export machinery and the structure and function of the Golgi apparatus, which might aid to escape cellular immune recognition.

  7. Surface-to-mountaintop transport characterised by radon observations at the Jungfraujoch

    Directory of Open Access Journals (Sweden)

    A. D. Griffiths

    2014-07-01

    Full Text Available Atmospheric composition measurements at Jungfraujoch are affected intermittently by thermally-driven (anabatic mountain winds as well as by other vertical transport mechanisms. Using radon-222 observations, and a new analysis method, we quantify the land surface influence hour-by-hour and detect the presence of anabatic winds on a daily basis. During 2010–2011, anabatic winds occurred on roughly 40% of days, but only from April–September. Anabatic wind days were associated with warmer air temperatures over a large fraction of Europe and with a shift in airmass properties. Shifts were evident even when comparing the same radon concentrations, a proxy for land-surface influence. Aerosol washout, when quantified as a function of rain-rate using a radon normalisation technique, was also influenced by anabatic winds being more pronounced on non-anabatic days. Excluding the influence of anabatic winds, however, did not lead to a better definition of the unperturbed aerosol background than a definition based on radon alone, supporting the use of a radon threshold to identify periods with weak land-surface influence.

  8. Formulation effects and the off-target transport of pyrethroid insecticides from urban hard surfaces.

    Science.gov (United States)

    Jorgenson, Brant C; Young, Thomas M

    2010-07-01

    Controlled rainfall experiments utilizing drop-forming rainfall simulators were conducted to study various factors contributing to off-target transport of off-the-shelf formulated pyrethroid insecticides from concrete surfaces. Factors evaluated included active ingredient, product formulation, time between application and rainfall (set time), and rainfall intensity. As much as 60% and as little as 0.8% of pyrethroid applied could be recovered in surface runoff depending primarily on product formulation, and to a lesser extent on product set time. Resulting wash-off profiles during one-hour storm simulations could be categorized based on formulation, with formulations utilizing emulsifying surfactants rather than organic solvents resulting in unique wash-off profiles with overall higher wash-off efficiency. These higher wash-off efficiency profiles were qualitatively replicated by applying formulation-free neat pyrethroid in the presence of independently applied linear alkyl benzene sulfonate (LAS) surfactant, suggesting that the surfactant component of some formulated products may be influential in pyrethroid wash-off from urban hard surfaces.

  9. Development of a Dynamically Scaled Generic Transport Model Testbed for Flight Research Experiments

    Science.gov (United States)

    Jordan, Thomas; Langford, William; Belcastro, Christine; Foster, John; Shah, Gautam; Howland, Gregory; Kidd, Reggie

    2004-01-01

    This paper details the design and development of the Airborne Subscale Transport Aircraft Research (AirSTAR) test-bed at NASA Langley Research Center (LaRC). The aircraft is a 5.5% dynamically scaled, remotely piloted, twin-turbine, swept wing, Generic Transport Model (GTM) which will be used to provide an experimental flight test capability for research experiments pertaining to dynamics modeling and control beyond the normal flight envelope. The unique design challenges arising from the dimensional, weight, dynamic (inertial), and actuator scaling requirements necessitated by the research community are described along with the specific telemetry and control issues associated with a remotely piloted subscale research aircraft. Development of the necessary operational infrastructure, including operational and safety procedures, test site identification, and research pilots is also discussed. The GTM is a unique vehicle that provides significant research capacity due to its scaling, data gathering, and control characteristics. By combining data from this testbed with full-scale flight and accident data, wind tunnel data, and simulation results, NASA will advance and validate control upset prevention and recovery technologies for transport aircraft, thereby reducing vehicle loss-of-control accidents resulting from adverse and upset conditions.

  10. Transport and scavenging of Pu in surface waters of the Southern Hemisphere Oceans

    DEFF Research Database (Denmark)

    Gastaud, J.; Povinec, P.P.; Aoyama, M.

    2011-01-01

    The distribution of 239Pu in Atlantic and Indian Ocean waters about four decades after their main injection from atmospheric nuclear weapons tests is discussed. Recent data obtained in the framework of the SHOTS (Southern Hemisphere Ocean Tracer Studies) projects are evaluated and compared...... with previous investigations. Seawater samples were collected during the round the globe BEAGLE2003 (Blue Ocean Global Expedition) along the 30°S transect in the Atlantic and the 20°S transect in the Indian Ocean. The results indicate transport of surface waters labelled with 239Pu from the western North...... Pacific via the Indonesian Seas to the South Indian Ocean and then to the South Atlantic Ocean. Along the whole BEAGLE2003 sampling route, the Atlantic Ocean has the lowest 239Pu content due to its particle scavenging on the long way from the western North Pacific. On the other hand, concentrations...

  11. Using Contaminant Transport Modeling to Determine Historical Discharges at the Surface

    Science.gov (United States)

    Fogwell, T. W.

    2013-12-01

    When it is determined that a contaminated site needs to be remediated, the issue of who is going to pay for that remediation is an immediate concern. This means that there needs to be a determination of who the responsible parties are for the existing contamination. Seldom is it the case that records have been made and kept of the surface contaminant discharges. In many cases it is possible to determine the relative amount of contaminant discharge at the surface of the various responsible parties by employing a careful analysis of the history of contaminant transport through the surface, through the vadose zone, and within the saturated zone. The process begins with the development of a dynamic conceptual site model that takes into account the important features of the transport of the contaminants through the vadose zone and in the groundwater. The parameters for this model can be derived from flow data available for the site. The resulting contaminant transport model is a composite of the vadose zone transport model, together with the saturated zone (groundwater) flow model. Any calibration of the model should be carefully employed in order to avoid using information about the conclusions of the relative discharge amounts of the responsible parties in determining the calibrated parameters. Determination of the leading edge of the plume is an important first step. It is associated with the first discharges from the surface of the site. If there were several discharging parties at the same time, then it is important to establish a chemical or isotopic signature of the chemicals that were discharged. The time duration of the first discharger needs to be determined as accurately as possible in order to establish the appropriate characterization of the leading portion of the resulting plume in the groundwater. The information about the first discharger and the resulting part of the plume associated with this discharger serves as a basis for the determination of the

  12. Can Surface Flux Transport Account for the Weak Polar Field in Cycle 23?

    Science.gov (United States)

    Jiang, Jie; Cameron, Robert H.; Schmitt, Dieter; Schüssler, Manfred

    2013-06-01

    To reproduce the weak magnetic field on the polar caps of the Sun observed during the declining phase of cycle 23 poses a challenge to surface flux transport models since this cycle has not been particularly weak. We use a well-calibrated model to evaluate the parameter changes required to obtain simulated polar fields and open flux that are consistent with the observations. We find that the low polar field of cycle 23 could be reproduced by an increase of the meridional flow by 55% in the last cycle. Alternatively, a decrease of the mean tilt angle of sunspot groups by 28% would also lead to a similarly low polar field, but cause a delay of the polar field reversals by 1.5 years in comparison to the observations.

  13. Can surface flux transport account for the weak polar field in cycle 23?

    CERN Document Server

    Jiang, Jie; Schmitt, Dieter; Schuessler, Manfred

    2011-01-01

    To reproduce the weak magnetic field on the polar caps of the Sun observed during the declining phase of cycle 23 poses a challenge to surface flux transport models since this cycle has not been particularly weak. We use a well-calibrated model to evaluate the parameter changes required to obtain simulated polar fields and open flux that are consistent with the observations. We find that the low polar field of cycle 23 could be reproduced by an increase of the meridional flow by 55% in the last cycle. Alternatively, a decrease of the mean tilt angle of sunspot groups by 28% would also lead to a similarly low polar field, but cause a delay of the polar field reversals by 1.5 years in comparison to the observations.

  14. Simulation of soluble waste transport and buildup in surface waters using tracers

    Science.gov (United States)

    Kilpatrick, F.A.

    1993-01-01

    Soluble tracers can be used to simulate the transport and dispersion of soluble wastes that might have been introduced or are planned for introduction into surface waters. Measured tracer-response curves produced from the injection of a known quantity of soluble tracer can be used in conjunction with the superposition principle to simulate potential waste buildup in streams, lakes, and estuaries. Such information is particularly valuable to environmental and water-resource planners in determining the effects of proposed waste discharges. The theory, techniques, analysis, and presentation of results of tracer-waste simulation tests in rivers, lakes, and estuaries are described. This manual builds on other manuals dealing with dye tracing by emphasizing the expanded use of data from time-of-travel studies.

  15. Fundamental and applied research in hydraulic transportation at the CSIR, Pretoria, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Sauermann, H.B.

    1983-03-01

    The paper outlines the type of work on hydraulic transportation of solids which has been and is being carried out by the National Mechanical Engineering Research Institute at Pretoria. Special emphasis is placed on handling mineral slurries, since the mining industry plays an important part in the South African economy. (7 refs.)

  16. Fundamental and applied research in hydraulic transportation at the CSIR, Pretoria, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Sauermann, H.B.

    1983-03-01

    This article outlines the type of work on hydraulic transportation of solids which has been and is being carried out by the National Mechanical Engineering Research Institute at Pretoria. Special emphasis is placed on handling mineral slurries, since the mining industry plays an important part in the South African economy.

  17. From the surface to the seafloor: How giant larvaceans transport microplastics into the deep sea.

    Science.gov (United States)

    Katija, Kakani; Choy, C Anela; Sherlock, Rob E; Sherman, Alana D; Robison, Bruce H

    2017-08-01

    Plastic waste is a pervasive feature of marine environments, yet little is empirically known about the biological and physical processes that transport plastics through marine ecosystems. To address this need, we conducted in situ feeding studies of microplastic particles (10 to 600 μm in diameter) with the giant larvacean Bathochordaeus stygius. Larvaceans are abundant components of global zooplankton assemblages, regularly build mucus "houses" to filter particulate matter from the surrounding water, and later abandon these structures when clogged. By conducting in situ feeding experiments with remotely operated vehicles, we show that giant larvaceans are able to filter a range of microplastic particles from the water column, ingest, and then package microplastics into their fecal pellets. Microplastics also readily affix to their houses, which have been shown to sink quickly to the seafloor and deliver pulses of carbon to benthic ecosystems. Thus, giant larvaceans can contribute to the vertical flux of microplastics through the rapid sinking of fecal pellets and discarded houses. Larvaceans, and potentially other abundant pelagic filter feeders, may thus comprise a novel biological transport mechanism delivering microplastics from surface waters, through the water column, and to the seafloor. Our findings necessitate the development of tools and sampling methodologies to quantify concentrations and identify environmental microplastics throughout the water column.

  18. Surface Flux Transport and the Evolution of the Sun's Polar Fields

    Science.gov (United States)

    Wang, Y.-M.

    2017-09-01

    The evolution of the polar fields occupies a central place in flux transport (Babcock-Leighton) models of the solar cycle. We discuss the relationship between surface flux transport and polar field evolution, focusing on two main issues: the latitudinal profile of the meridional flow and the axial tilts of active regions. Recent helioseismic observations indicate that the poleward flow speed peaks at much lower latitudes than inferred from magnetic feature tracking, which includes the effect of supergranular diffusion and thus does not represent the actual bulk flow. Employing idealized simulations, we demonstrate that flow profiles that peak at mid latitudes give rise to overly strong and concentrated polar fields. We discuss the differences between magnetic and white-light measurements of tilt angles, noting the large uncertainties inherent in the sunspot group measurements and their tendency to underestimate the actual tilts. We find no clear evidence for systematic cycle-to-cycle variations in Joy's law during cycles 21-23. Finally, based on the observed evolution of the Sun's axial dipole component and polar fields up to the end of 2015, we predict that cycle 25 will be similar in amplitude to cycle 24.

  19. Transport and retention of phosphorus in surface water in an urban slum area

    Science.gov (United States)

    Nyenje, P. M.; Meijer, L. M. G.; Foppen, J. W.; Kulabako, R.; Uhlenbrook, S.

    2013-08-01

    The transport of excessive phosphorus (P) discharged from unsewered informal settlements (slums) due to poor on-site sanitation is largely unknown. Hence, we investigated the processes governing P transport in a 28 km2 slum-dominated catchment in Kampala, Uganda. During high runoff events and a period of base flow, we collected hourly water samples (over 24 h) from a primary channel draining the catchment and from a small size tertiary channel draining one of the contributing slum areas (0.5 km2). Samples were analyzed for orthophosphate (PO4-P), particulate P (PP), total P (TP) and selected hydro-chemical parameters. Channel bed and suspended sediments were collected to determine their sorption potential, geo-available metals and dominant P forms. We found that P inputs in the catchment originated mainly from domestic wastewater as evidenced by high concentrations of Cl (36-144 mg L-1), HCO3 and other cations in the channels. Most P discharged during low flow conditions was particulate implying that much of it was retained in bed sediments. Retained P was mostly bound to Ca and Fe/Al oxides. Hence, we inferred that mineral precipitation and adsorption to Ca-minerals were the dominant P retention processes. Bed sediments were P-saturated and showed a tendency to release P to discharging waters. P released was likely due to Ca-bound P because of the strong correlation between Ca and total P in sediments (r2 = 0.9). High flows exhibited a strong flush of PP and SS implying that part of P retained was frequently flushed out of the catchment by surface erosion and resuspension of bed sediment. Our findings suggest that P accumulated in the channel bed during low flows and then was slowly released into surface water. Hence, it will likely take some time, even with improved wastewater management practices, before P loads to downstream areas can be significantly reduced.

  20. Transport and retention of phosphorus in surface water in an urban slum area

    Directory of Open Access Journals (Sweden)

    P. M. Nyenje

    2013-08-01

    Full Text Available The transport of excessive phosphorus (P discharged from unsewered informal settlements (slums due to poor on-site sanitation is largely unknown. Hence, we investigated the processes governing P transport in a 28 km2 slum-dominated catchment in Kampala, Uganda. During high runoff events and a period of base flow, we collected hourly water samples (over 24 h from a primary channel draining the catchment and from a small size tertiary channel draining one of the contributing slum areas (0.5 km2. Samples were analyzed for orthophosphate (PO4-P, particulate P (PP, total P (TP and selected hydro-chemical parameters. Channel bed and suspended sediments were collected to determine their sorption potential, geo-available metals and dominant P forms. We found that P inputs in the catchment originated mainly from domestic wastewater as evidenced by high concentrations of Cl (36–144 mg L-1, HCO3 and other cations in the channels. Most P discharged during low flow conditions was particulate implying that much of it was retained in bed sediments. Retained P was mostly bound to Ca and Fe/Al oxides. Hence, we inferred that mineral precipitation and adsorption to Ca-minerals were the dominant P retention processes. Bed sediments were P-saturated and showed a tendency to release P to discharging waters. P released was likely due to Ca-bound P because of the strong correlation between Ca and total P in sediments (r2 = 0.9. High flows exhibited a strong flush of PP and SS implying that part of P retained was frequently flushed out of the catchment by surface erosion and resuspension of bed sediment. Our findings suggest that P accumulated in the channel bed during low flows and then was slowly released into surface water. Hence, it will likely take some time, even with improved wastewater management practices, before P loads to downstream areas can be significantly reduced.

  1. Cell surface receptors for signal transduction and ligand transport: a design principles study.

    Directory of Open Access Journals (Sweden)

    Harish Shankaran

    2007-06-01

    Full Text Available Receptors constitute the interface of cells to their external environment. These molecules bind specific ligands involved in multiple processes, such as signal transduction and nutrient transport. Although a variety of cell surface receptors undergo endocytosis, the systems-level design principles that govern the evolution of receptor trafficking dynamics are far from fully understood. We have constructed a generalized mathematical model of receptor-ligand binding and internalization to understand how receptor internalization dynamics encodes receptor function and regulation. A given signaling or transport receptor system represents a particular implementation of this module with a specific set of kinetic parameters. Parametric analysis of the response of receptor systems to ligand inputs reveals that receptor systems can be characterized as being: i avidity-controlled where the response control depends primarily on the extracellular ligand capture efficiency, ii consumption-controlled where the ability to internalize surface-bound ligand is the primary control parameter, and iii dual-sensitivity where both the avidity and consumption parameters are important. We show that the transferrin and low-density lipoprotein receptors are avidity-controlled, the vitellogenin receptor is consumption-controlled, and the epidermal growth factor receptor is a dual-sensitivity receptor. Significantly, we show that ligand-induced endocytosis is a mechanism to enhance the accuracy of signaling receptors rather than merely serving to attenuate signaling. Our analysis reveals that the location of a receptor system in the avidity-consumption parameter space can be used to understand both its function and its regulation.

  2. Evaluation of influence of surface barrier in solid on ion reflection by bipartition model of ion transport

    Institute of Scientific and Technical Information of China (English)

    YANG Dai-Lun; WU Zhang-Wen

    2004-01-01

    The influence of surface barrier of solid upon ion reflection was studied in a few papers of other authors by using the Monte-Carlo simulation. Based on the bipartition model of ion transport, a new analytical theory has been developed instead of the MC simulation, due to important implication of the effect for fusion research. In the present paper we have calculated the number reflection coefficients of H+, D+, He and T+ normally incident on C,Al and Cu for ion energy from several eV to one hundred keV respectively. Our computational results accorded with the MC simulation. The results have shown that the effect of surface barrier on ion reflection becomes evident when the energy of incident ions is lower than one keV. In particular, for the ion energy from several eV to one hun dred eV, the discrepancies of number reflection coefficients can increase up to 0.1~0.3, showing this influence to be very important.

  3. Effects of noradrenaline on the cell-surface glucose transporters in cultured brown adipocytes: novel mechanism for selective activation of GLUT1 glucose transporters.

    Science.gov (United States)

    Shimizu, Y; Satoh, S; Yano, H; Minokoshi, Y; Cushman, S W; Shimazu, T

    1998-01-01

    Glucose transport into rat brown adipocytes has been shown to be stimulated directly by the sympathetic neurotransmitter, noradrenaline, without a significant increase in the protein content of either GLUT1 or GLUT4 glucose transporter in the plasma membrane [Shimizu, Kielar, Minokoshi and Shimazu (1996) Biochem. J. 314, 485-490]. In the present study, we labelled the exofacial glucose-binding sites of GLUT1 and GLUT4 with a membrane-impermeant photoaffinity reagent, 2-N-[4-(1-azitrifluoroethyl)benzoyl]-[2-3H]1,3-bis- (D-mannos-4-yloxy)-2-propylamine (ATB-[3H]BMPA), to determine which isoform is responsible for the noradrenaline-induced increase in glucose transport into intact brown adipocytes in culture. Insulin stimulated the rate of hexose transport by increasing ATB-[3H]BMPA-labelled cell-surface GLUT4. In contrast, the noradrenaline-induced increase in glucose transport was not accompanied by an increased ATB-[3H]BMPA labelling of GLUT4, nor with an increased amount of GLUT4 in the plasma membrane fraction as assessed by Western blotting, indicating that noradrenaline does not promote the translocation of GLUT4. However, noradrenaline induced an increase in photoaffinity labelling of cell-surface GLUT1 without an apparent increase in the immunoreactive GLUT1 protein in the plasma membrane. This is suggestive of an increased affinity of GLUT1 for the ligand. In fact, the Ki value of non-radioactive ATB-BMPA for 2-deoxy-D-glucose uptake was significantly decreased after treatment of the cells with noradrenaline. The increased photoaffinity labelling of GLUT1 and increased glucose transport caused by noradrenaline were inhibited by a cAMP antagonist, cAMP-S Rp-isomer. These results demonstrate that noradrenaline stimulates glucose transport in brown adipocytes by enhancing the functional activity of GLUT1 through a cAMP-dependent mechanism. PMID:9461536

  4. Comparing Methods of Separating Bacterial Biofilms on the Surface of Water Transportation Pipes and Equipment of Milking in the Farms

    Directory of Open Access Journals (Sweden)

    setareh nabizadeh

    2016-08-01

    Full Text Available Introduction Bacterial biofilms can be both useful and harmful based on their combination and locations. Biofilm formation occurs as a stepwise process. Their formation in liquid transportation pipes used for milking system and drinking water in animal farms may create some problems and is a potential source of pollution. Speed of biofilm formation depends on many factors including: construction and functional characteristics of bacteria, the composition and culture conditions such as temperature and substratum. In this research the Bacillus subtillis bacteria with special characteristics was selected due to its capability for biofilm creation. Bacillus subtillis bacteria is mobility and a stronger connection than other bacteria levels are created. In the research conducted in the biofilm there are many resources on biofilm formation by Bacillus subtillis bacteria. Bacillus subtillis is saprophytic in the soil, water and air. There is also the ability to form spores of Bacillus subtillis. Materials and Methods Firstly the possibility of creating biofilms on different Plastic (polyvinilchlorid, polypropylene, polyethylengelycole, alluminum and glass surfaces in three temperatures of 4°C, 30°C and 37°C were studied. Two different methods of biofilms separation including separating swap and vortex were tested and their efficienceies were calculated. After biofilm formation on parts of the vortex separation method after washing parts in sterile conditions in a tube containing normal saline for 4 minutes was vortex. The bacterial suspension decreasing dilution series was created. Pour plate in medium using agar plate count agar and was cultured at 30°C for 24-48 hours. Numbers of colonies were counted. The numbers of biofilm cells were calculated. In swap method after biofilm formation on parts using a cotton swap was isolated biofilms. The swap was transferred to tube containing normal saline and the bacterial suspension decreasing dilution

  5. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Glenn Charles [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    In this dissertation, results are presented of laboratory investigations and mathematical modeling efforts designed to better understand the interactions of ozone with surfaces. In the laboratory, carpet and duct materials were exposed to ozone and measured ozone uptake kinetics and the ozone induced emissions of volatile organic compounds. To understand the results of the experiments, mathematical methods were developed to describe dynamic indoor aldehyde concentrations, mass transport of reactive species to smooth surfaces, the equivalent reaction probability of whole carpet due to the surface reactivity of fibers and carpet backing, and ozone aging of surfaces. Carpets, separated carpet fibers, and separated carpet backing all tended to release aldehydes when exposed to ozone. Secondary emissions were mostly n-nonanal and several other smaller aldehydes. The pattern of emissions suggested that vegetable oils may be precursors for these oxidized emissions. Several possible precursors and experiments in which linseed and tung oils were tested for their secondary emission potential were discussed. Dynamic emission rates of 2-nonenal from a residential carpet may indicate that intermediate species in the oxidation of conjugated olefins can significantly delay aldehyde emissions and act as reservoir for these compounds. The ozone induced emission rate of 2-nonenal, a very odorous compound, can result in odorous indoor concentrations for several years. Surface ozone reactivity is a key parameter in determining the flux of ozone to a surface, is parameterized by the reaction probability, which is simply the probability that an ozone molecule will be irreversibly consumed when it strikes a surface. In laboratory studies of two residential and two commercial carpets, the ozone reaction probability for carpet fibers, carpet backing and the equivalent reaction probability for whole carpet were determined. Typically reaction probability values for these materials were 10

  6. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Glenn C.

    1999-12-01

    In this dissertation, results are presented of laboratory investigations and mathematical modeling efforts designed to better understand the interactions of ozone with surfaces. In the laboratory, carpet and duct materials were exposed to ozone and measured ozone uptake kinetics and the ozone induced emissions of volatile organic compounds. To understand the results of the experiments, mathematical methods were developed to describe dynamic indoor aldehyde concentrations, mass transport of reactive species to smooth surfaces, the equivalent reaction probability of whole carpet due to the surface reactivity of fibers and carpet backing, and ozone aging of surfaces. Carpets, separated carpet fibers, and separated carpet backing all tended to release aldehydes when exposed to ozone. Secondary emissions were mostly n-nonanal and several other smaller aldehydes. The pattern of emissions suggested that vegetable oils may be precursors for these oxidized emissions. Several possible precursors and experiments in which linseed and tung oils were tested for their secondary emission potential were discussed. Dynamic emission rates of 2-nonenal from a residential carpet may indicate that intermediate species in the oxidation of conjugated olefins can significantly delay aldehyde emissions and act as reservoir for these compounds. The ozone induced emission rate of 2-nonenal, a very odorous compound, can result in odorous indoor concentrations for several years. Surface ozone reactivity is a key parameter in determining the flux of ozone to a surface, is parameterized by the reaction probability, which is simply the probability that an ozone molecule will be irreversibly consumed when it strikes a surface. In laboratory studies of two residential and two commercial carpets, the ozone reaction probability for carpet fibers, carpet backing and the equivalent reaction probability for whole carpet were determined. Typically reaction probability values for these materials were 10

  7. Theoretical investigation of the electronic structure and quantum transport in the graphene-C(111) diamond surface system.

    Science.gov (United States)

    Selli, Daniele; Baburin, Igor; Leoni, Stefano; Zhu, Zhen; Tománek, David; Seifert, Gotthard

    2013-10-30

    We investigate the interaction of a graphene monolayer with the C(111) diamond surface using ab initio density functional theory. To accommodate the lattice mismatch between graphene and diamond, the overlayer deforms into a wavy structure that binds strongly to the diamond substrate. The detached ridges of the wavy graphene overlayer behave electronically as free-standing polyacetylene chains with delocalized π electrons, separated by regions containing only sp(3) carbon atoms covalently bonded to the (111) diamond surface. We performed quantum transport calculations for different geometries of the system to study how the buckling of the graphene layer and the associated bonding to the diamond substrate affect the transport properties. The system displays high carrier mobility along the ridges and a wide transport gap in the direction normal to the ridges. These intriguing, strongly anisotropic transport properties qualify the hybrid graphene-diamond system as a viable candidate for electronic nanodevices.

  8. A model for the biosynthesis and transport of plasma membrane-associated signaling receptors to the cell surface

    Directory of Open Access Journals (Sweden)

    Sorina Claudia Popescu

    2012-04-01

    Full Text Available Intracellular protein transport is emerging as critical in determining the outcome of receptor-activated signal transduction pathways. In plants, relatively little is known about the nature of the molecular components and mechanisms involved in coordinating receptor synthesis and transport to the cell surface. Recent advances in this field indicate that signaling pathways and intracellular transport machinery converge and coordinate to render receptors competent for signaling at their plasma membrane activity sites. The biogenesis and transport to the cell surface of signaling receptors appears to require both general trafficking and receptor-specific factors. Several molecular determinants, residing or associated with compartments of the secretory pathway and known to influence aspects in receptor biogenesis, are discussed and integrated into a predictive cooperative model for the functional expression of signaling receptors at the plasma membrane.

  9. Transport of Dirac fermions on the surface of strong topological insulator and graphene

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Arijit

    2012-06-14

    In this dissertation I study electronic transport through Dirac Fermions on the surface of strong topological insulator and graphene. I start by reviewing the physics of topological insulator and graphene and the low energy effective theory for the electronic states of the surface of a 3D strong topological insulator and graphene. Using this theory the electronic structure of the surface states of strong topological insulators of geometries with large surface to bulk ratio like nanowire and thin film are obtained. Then the energy spectrum and the spin-parity structure of the eigenstates for a finite size topological insulator quantum dot of the shape of a nanotube are considered. Numerical calculations show that even at the lowest energy scales, the ''spin-surface locking'' is broken, that is, the spin direction in a topologically protected surface mode is not locked to the surface. The calculations also show the existence of ''zero-momentum'' modes, and sub-gap states localized near the ''caps'' of the dot. Both the energy spectrum and the spin texture of the eigenstates are basically reproduced from an analytical surface Dirac fermion description. The results are compared to microscopic calculations using a tight-binding model for a strong topological insulator in a finite-length nanowire geometry, which shows qualitative similarity. Then, a theoretical study of electron-phonon scattering effects in thin films made of a strong topological insulator is presented. Phonons are modeled by isotropic elastic continuum theory with stress-free boundary conditions, and the interaction with the helical surface Dirac fermions is mediated by the deformation potential. The temperature-dependent electrical resistivity ρ(T) and the quasi-particle decay rate Γ(T) observable in photo-emission are computed numerically. The low and high-temperature power laws for both quantities are obtained analytically. Detailed

  10. Spatio-Temporal Modelling of Dust Transport over Surface Mining Areas and Neighbouring Residential Zones

    Directory of Open Access Journals (Sweden)

    Eva Gulikova

    2008-06-01

    Full Text Available Projects focusing on spatio-temporal modelling of the living environment need to manage a wide range of terrain measurements, existing spatial data, time series, results of spatial analysis and inputs/outputs from numerical simulations. Thus, GISs are often used to manage data from remote sensors, to provide advanced spatial analysis and to integrate numerical models. In order to demonstrate the integration of spatial data, time series and methods in the framework of the GIS, we present a case study focused on the modelling of dust transport over a surface coal mining area, exploring spatial data from 3D laser scanners, GPS measurements, aerial images, time series of meteorological observations, inputs/outputs form numerical models and existing geographic resources. To achieve this, digital terrain models, layers including GPS thematic mapping, and scenes with simulation of wind flows are created to visualize and interpret coal dust transport over the mine area and a neighbouring residential zone. A temporary coal storage and sorting site, located near the residential zone, is one of the dominant sources of emissions. Using numerical simulations, the possible effects of wind flows are observed over the surface, modified by natural objects and man-made obstacles. The coal dust drifts with the wind in the direction of the residential zone and is partially deposited in this area. The simultaneous display of the digital map layers together with the location of the dominant emission source, wind flows and protected areas enables a risk assessment of the dust deposition in the area of interest to be performed. In order to obtain a more accurate simulation of wind flows over the temporary storage and sorting site, 3D laser scanning and GPS thematic mapping are used to create a more detailed digital terrain model. Thus, visualization of wind flows over the area of interest combined with 3D map layers enables the exploration of the processes of coal dust

  11. Application research on big data in energy conservation and emission reduction of transportation industry

    Science.gov (United States)

    Bai, Bingdong; Chen, Jing; Wang, Mei; Yao, Jingjing

    2017-06-01

    In the context of big data age, the energy conservation and emission reduction of transportation is a natural big data industry. The planning, management, decision-making of energy conservation and emission reduction of transportation and other aspects should be supported by the analysis and forecasting of large amounts of data. Now, with the development of information technology, such as intelligent city, sensor road and so on, information collection technology in the direction of the Internet of things gradually become popular. The 3G/4G network transmission technology develop rapidly, and a large number of energy conservation and emission reduction of transportation data is growing into a series with different ways. The government not only should be able to make good use of big data to solve the problem of energy conservation and emission reduction of transportation, but also to explore and use a large amount of data behind the hidden value. Based on the analysis of the basic characteristics and application technology of energy conservation and emission reduction of transportation data, this paper carries out its application research in energy conservation and emission reduction of transportation industry, so as to provide theoretical basis and reference value for low carbon management.

  12. Mechanisms of nanoparticle internalization and transport across an intestinal epithelial cell model: effect of size and surface charge.

    Science.gov (United States)

    Bannunah, Azzah M; Vllasaliu, Driton; Lord, Jennie; Stolnik, Snjezana

    2014-12-01

    This study investigated the effect of nanoparticle size (50 and 100 nm) and surface charge on their interaction with Caco-2 monolayers as a model of the intestinal epithelium, including cell internalization pathways and the level of transepithelial transport. Initially, toxicity assays showed that cell viability and cell membrane integrity were dependent on the surface charge and applied mass, number, and total surface area of nanoparticles, as tested in two epithelial cell lines, colon carcinoma Caco-2 and airway Calu-3. This also identified suitable nanoparticle concentrations for subsequent cell uptake experiments. Nanoparticle application at doses below half maximal effective concentration (EC₅₀) revealed that the transport efficiency (ratio of transport to cell uptake) across Caco-2 cell monolayers is significantly higher for negatively charged nanoparticles compared to their positively charged counterparts (of similar size), despite the higher level of internalization of positively charged systems. Cell internalization pathways were hence probed using a panel of pharmacological inhibitors aiming to establish whether the discrepancy in transport efficiency is due to different uptake and transport pathways. Vesicular trans-monolayer transport for both positively and negatively charged nanoparticles was confirmed via inhibition of dynamin (by dynasore) and microtubule network (via nocodazole), which significantly reduced the transport of both nanoparticle systems. For positively charged nanoparticles a significant decrease in internalization and transport (46% and 37%, respectively) occurred in the presence of a clathrin pathway inhibitor (chlorpromazine), macropinocytosis inhibition (42%; achieved by 5-(N-ethyl-N-isopropyi)-amiloride), and under cholesterol depletion (38%; via methyl-β-cyclodextrin), but remained unaffected by the inhibition of lipid raft associated uptake (caveolae) by genistein. On the contrary, the most prominent reduction in

  13. Thermal transport study across interface “nanostructured solid surface / fluid” by photoacoustic technique

    Science.gov (United States)

    Voitenko, K.; Isaiev, M.; Pastushenko, A.; Andrusenko, D.; Kuzmich, A.; Lysenko, V.; Burbelo, R.

    2017-01-01

    In the paper the experimental study of heat transport across the interface “porous silicon/liquid” by photoacoustic technique is reported. Two cases with and without liquid covering of porous silicon surface were considered. Thermal perturbations were excited at the surface of porous silicon as a result of absorption of the light with modulated intensity. The resulting thermal-elastic stresses arising in the system were registered with piezoelectric transducer. The amplitude-frequency dependencies of the voltage on the piezoelectric electrodes were measured. The presence of the liquid film leads to decreasing of the amplitude of photoacoustic signal as a result of the thermal energy evacuation from the porous silicon into the liquid. The experimental dependencies were fitted with the results of simulation that takes into account heat fluxes separation at the porous silicon/liquid interface. With the presented method one can precisely measure heat fluxes transferred from the solid into contacting fluid. Moreover, the presented approach can be easily adopted for the thermal conductivity study of the different nanofluids as well as thermal resistance at the interface nanostructured solid/fluid.

  14. Hydrogen Research for Spaceport and Space-Based Applications: Hydrogen Production, Storage, and Transport. Part 3

    Science.gov (United States)

    Anderson, Tim; Balaban, Canan

    2008-01-01

    The activities presented are a broad based approach to advancing key hydrogen related technologies in areas such as fuel cells, hydrogen production, and distributed sensors for hydrogen-leak detection, laser instrumentation for hydrogen-leak detection, and cryogenic transport and storage. Presented are the results from research projects, education and outreach activities, system and trade studies. The work will aid in advancing the state-of-the-art for several critical technologies related to the implementation of a hydrogen infrastructure. Activities conducted are relevant to a number of propulsion and power systems for terrestrial, aeronautics and aerospace applications. Hydrogen storage and in-space hydrogen transport research focused on developing and verifying design concepts for efficient, safe, lightweight liquid hydrogen cryogenic storage systems. Research into hydrogen production had a specific goal of further advancing proton conducting membrane technology in the laboratory at a larger scale. System and process trade studies evaluated the proton conducting membrane technology, specifically, scale-up issues.

  15. Expanded serial communication capability for the transport systems research vehicle laptop computers

    Science.gov (United States)

    Easley, Wesley C.

    1991-01-01

    A recent upgrade of the Transport Systems Research Vehicle (TSRV) operated by the Advanced Transport Operating Systems Program Office at the NASA Langley Research Center included installation of a number of Grid 1500 series laptop computers. Each unit is a 80386-based IBM PC clone. RS-232 data busses are needed for TSRV flight research programs, and it has been advantageous to extend the application of the Grids in this area. Use was made of the expansion features of the Grid internal bus to add a user programmable serial communication channel. Software to allow use of the Grid bus expansion has been written and placed in a Turbo C library for incorporation into applications programs in a transparent manner via function calls. Port setup; interrupt-driven, two-way data transfer; and software flow control are built into the library functions.

  16. Surface States Transport in Topological Insulator Bi_{0.83}Sb_{0.17} Nanowires

    Science.gov (United States)

    Konopko, L. A.; Nikolaeva, A. A.; Huber, T. E.; Ansermet, J.-P.

    2016-12-01

    We investigate the transport properties of topological insulator (TI) Bi_{0.83}Sb_{0.17} nanowires. Single-crystal nanowire samples with diameters ranging from 75 nm to 1.1 μ m are prepared using high frequency liquid phase casting in a glass capillary; cylindrical single crystals with (10bar{1}1) orientation along the wire axis are produced. Bi_{0.83}Sb_{0.17} is a narrow-gap semiconductor with an energy gap at the L point of the Brillouin zone, Δ E = 21 meV. The resistance of the samples increases with decreasing temperature, but a decrease in resistance is observed at low temperatures. This effect is a clear manifestation of TI properties (i.e., the presence of a highly conducting zone on the TI surface). When the diameter of the nanowire decreases, the energy gap Δ E grows as 1 / d (for diameter d = 1.1 μ m and d =75 nm Δ E = 21 and 45 meV, respectively), which proves the presence of the quantum size effect in these samples. We investigate the magnetoresistance of Bi_{0.83}Sb_{0.17} nanowires at various magnetic field orientations. Shubnikov-de Haas oscillations are observed in Bi_{0.83}Sb_{0.17} nanowires at T = 1.5 K, demonstrating the existence of high mobility (μ_S = 26{,}700-47{,}000 cm^2V^{-1}s^{-1}) two-dimensional (2D) carriers in the surface areas of the nanowires, which are nearly perpendicular to the C_3 axis. From the linear dependence of the nanowire conductance on nanowire diameter at T = 4.2 K, the square resistance R_sq of the surface states of the nanowires is obtained (R_sq =70 Ohm).

  17. Phonon transport in silicon nanowires: The reduced group velocity and surface-roughness scattering

    Science.gov (United States)

    Zhu, Liyan; Li, Baowen; Li, Wu

    2016-09-01

    Using a linear-scaling Kubo simulation approach, we have quantitatively investigated the effects of confinement and surface roughness on phonon transport in silicon nanowires (SiNWs) as thick as 55 nm in diameter R . The confinement effect leads to significant reduction of phonon group velocity v in SiNWs compared to bulk silicon except at extremely low phonon frequencies f , which very likely persists in SiNWs several hundreds of nanometers thick, suggesting the inapplicability of bulk properties, including anharmonic phonon scattering, to SiNWs. For instance, the velocity can be reduced by more than 30% for phonons with f >4.5 THz in 55-nm-thick nanowires. In rough SiNWs Casimir's limit, which is valid in confined macroscopic systems, can underestimate the surface scattering by more than one order of magnitude. For a roughness profile with Lorentzian correlation characterized by root-mean-square roughness σ and correlation length Lr, the frequency-dependent phonon diffusivity D follows power-law dependences D ∝Rασ-βLrγ , where α ˜2 and β ˜1 . On average, γ increases from 0 to 0.5 as R /σ increases. The mean free path and the phonon lifetime essentially follow the same power-law dependences. These dependences are in striking contrast to Casimir's limit, i.e., D ˜v R /3 , and manifest the dominant role of the change in the number of atoms due to roughness. The thermal conductivity κ can vary by one order of magnitude with varying σ and Lr in SiNWs, and increasing σ and shortening Lr can efficiently lower κ below Casimir's limit by one order of magnitude. Our work provides different insights to understand the ultralow thermal conductivity of SiNWs reported experimentally and guidance to manipulate κ via surface roughness engineering.

  18. Surface-Water to Groundwater Transport of Pharmaceuticals in a Wastewater-Impacted Stream in the U.S.

    Science.gov (United States)

    Bradley, P. M.; Barber, L. B.; Duris, J. W.; Foreman, W. T.; Furlong, E. T.; Hubbard, L. E.; Hutchinson, K. J.; Keefe, S. H.; Kolpin, D. W.

    2014-12-01

    Wastewater pharmaceutical contamination of shallow groundwater is a substantial concern in effluent-dominated streams, due to aqueous mobility and designed bioactivity of pharmaceuticals and due to effluent-driven hydraulic gradients. Improved understanding of the environmental fate and transport of wastewater-derived pharmaceuticals is essential for effective protection of vital aquatic ecosystem services, environmental health, and drinking-water supplies. Substantial longitudinal (downstream) transport of pharmaceutical contaminants has been documented in effluent-impacted streams. The comparative lack of information on vertical and lateral transport (infiltration) of wastewater contaminants from surface-water to hyporheic and shallow groundwater compartments is a critical scientific data gap, given the potential for contamination of groundwater supplies in effluent-impacted systems. Growing dependencies on bank filtration and artificial recharge applications for release of wastewater to the environment and for pretreatment of poor-quality surface-water for drinking water emphasize the critical need to better understand the exchange of wastewater contaminants, like pharmaceuticals, between surface-water and groundwater compartments. The potential transport of effluent-derived pharmaceutical contaminants from surface-water to hyporheic-water and shallow groundwater compartments was examined in a wastewater-treatment-facility (WWTF) impacted stream in Ankeny, Iowa under effluent-dominated (71-99% of downstream flow) conditions. Strong hydraulic gradients and hydrologic connectivity were evident between surface-water and shallow-groundwater compartments in the vicinity of the WWTF outfall. Carbamazepine, sulfamethoxazole, and immunologically-related compounds were detected in groundwater 10-20 meters from the stream bank. Direct aqueous-injection HPLC-MS/MS revealed high percentage detections of pharmaceuticals (110 total analytes) in surface-water and groundwater

  19. Shielding calculation and criticality safety analysis of spent fuel transportation cask in research reactors.

    Science.gov (United States)

    Mohammadi, A; Hassanzadeh, M; Gharib, M

    2016-02-01

    In this study, shielding calculation and criticality safety analysis were carried out for general material testing reactor (MTR) research reactors interim storage and relevant transportation cask. During these processes, three major terms were considered: source term, shielding, and criticality calculations. The Monte Carlo transport code MCNP5 was used for shielding calculation and criticality safety analysis and ORIGEN2.1 code for source term calculation. According to the results obtained, a cylindrical cask with body, top, and bottom thicknesses of 18, 13, and 13 cm, respectively, was accepted as the dual-purpose cask. Furthermore, it is shown that the total dose rates are below the normal transport criteria that meet the standards specified.

  20. Research on Complexity of Surface Undulating Shapes of Rock Joints

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The surface undulating shapes of rock joints have been described qualitatively or experimental-quantitatively for a long time. The non-determined describing method can not fit quantitative evaluation of mechanical parameters of rock joints in engineering. In this paper, relative amplitude (RA) is chosen as a quantitative-describing index of surface measurement of 1 023 surface undulating curves which conducted by profile curve device(PCD). We discuss the nonuniformity,anisotropy and unhomogeneity of surface undulating shapes of joints. A new method that analyzes the complexity of surface undulating shapes of rock joints directional-statistically in various rock joints is also put forward.

  1. Marketing Research on Passenger Satisfaction With Public Transport Service in the City of Belgrade

    Directory of Open Access Journals (Sweden)

    Branislav Radnović

    2015-03-01

    Full Text Available The aim of this paper is to determine, based on conducted marketing research, the level of passenger satisfaction with public transport services for the purpose of making better marketing decisions in the example of the City of Belgrade. The main task is to test the hypothesis on the existence of significant influence of factors, such as quality service, attitude and behaviour of employees (e.g. driver, adequate informing, quality of vehicles, line routes and timetable, on passenger satisfaction. Correlation coefficient and regression analysis were used for interpreting the obtained results and examining the formulated hypothesis. Empirical research has shown that there is a significant correlation between the aforementioned factors and passenger satisfaction with public transport services. The obtained results provided recommendations and guidelines for improving and increasing the quality of public transport services. The research results also provide the basis for future research that could examine the relationship between passenger satisfaction with services and sub-groups within the analyzed factors.

  2. Application of divided convective-dispersive transport model to simulate conservative transport processes in planted horizontal sub-surface flow constructed wetlands.

    Science.gov (United States)

    Dittrich, Ernő; Klincsik, Mihály

    2015-11-01

    We have created a divided convective-dispersive transport (D-CDT) model that can be used to provide an accurate simulation of conservative transport processes in planted horizontal sub-surface flow constructed wetlands filled with coarse gravel (HSFCW-C). This model makes a fitted response curve from the sum of two independent CDT curves, which show the contributions of the main and side streams. The analytical solutions of both CDT curves are inverse Gaussian distribution functions. We used Fréchet distribution to provide a fast optimization mathematical procedure. As a result of our detailed analysis, we concluded that the most important role in the fast upward part of the tracer response curve is played by the main stream, with high porous velocity and dispersion. This gives the first inverse Gaussian distribution function. The side stream shows slower transport processes in the micro-porous system, and this shows the impact of back-mixing and dead zones, too. The significance of this new model is that it can simulate transport processes in this kind of systems more accurately than the conventionally used convective-dispersive transport (CDT) model. The calculated velocity and dispersion coefficients with the D-CDT model gave differences of 24-54% (of velocity) and 22-308% (of dispersion coeff.) from the conventional CDT model, and were closer to actual hydraulic behaviour.

  3. Influence of surface wettability on transport mechanisms governing water droplet evaporation.

    Science.gov (United States)

    Pan, Zhenhai; Weibel, Justin A; Garimella, Suresh V

    2014-08-19

    Prediction and manipulation of the evaporation of small droplets is a fundamental problem with importance in a variety of microfluidic, microfabrication, and biomedical applications. A vapor-diffusion-based model has been widely employed to predict the interfacial evaporation rate; however, its scope of applicability is limited due to incorporation of a number of simplifying assumptions of the physical behavior. Two key transport mechanisms besides vapor diffusion-evaporative cooling and natural convection in the surrounding gas-are investigated here as a function of the substrate wettability using an augmented droplet evaporation model. Three regimes are distinguished by the instantaneous contact angle (CA). In Regime I (CA ≲ 60°), the flat droplet shape results in a small thermal resistance between the liquid-vapor interface and substrate, which mitigates the effect of evaporative cooling; upward gas-phase natural convection enhances evaporation. In Regime II (60 ≲ CA ≲ 90°), evaporative cooling at the interface suppresses evaporation with increasing contact angle and counterbalances the gas-phase convection enhancement. Because effects of the evaporative cooling and gas-phase convection mechanisms largely neutralize each other, the vapor-diffusion-based model can predict the overall evaporation rates in this regime. In Regime III (CA ≳ 90°), evaporative cooling suppresses the evaporation rate significantly and reverses entirely the direction of natural convection induced by vapor concentration gradients in the gas phase. Delineation of these counteracting mechanisms reconciles previous debate (founded on single-surface experiments or models that consider only a subset of the governing transport mechanisms) regarding the applicability of the classic vapor-diffusion model. The vapor diffusion-based model cannot predict the local evaporation flux along the interface for high contact angle (CA ≥ 90°) when evaporative cooling is strong and the

  4. Contributions of regional and intercontinental transport to surface ozone in Tokyo

    Science.gov (United States)

    Yoshitomi, M.; Wild, O.; Akimoto, H.

    2011-04-01

    Japan lies downwind of the Asian continent and for much of the year air quality is directly influenced by emissions of ozone precursors over these heavily-populated and rapidly-industrializing regions. This study examines the extent to which oxidant transport from regional and distant anthropogenic sources influences air quality in Japan in springtime, when these contributions are largest. We find that European and North American contributions to surface ozone over Japan in spring are persistent, averaging 3.5±1.1 ppb and 2.8±0.5 ppb respectively, and are greatest in cold continental outflow conditions following the passage of cold fronts. Contributions from China are larger, 4.0±2.8 ppb, and more variable, as expected for a closer source region, and are generally highest near cold fronts preceding the influence of more distant sources. The stratosphere provides a varying but ever-present background of ozone of about 11.2±2.5 ppb during spring. Local sources over Japan and Korea have a relatively small impact on mean ozone, 2.4±7.6 ppb, but this masks a strong diurnal signal, and local sources clearly dominate during episodes of high daytime ozone. By examining the meteorological mechanisms that favour transport from different source regions, we demonstrate that while maximum foreign influence generally does not occur at the same time as the greatest buildup of oxidants from local sources, it retains a significant influence under these conditions. It is thus clear that while meteorological boundaries provide some protection from foreign influence during oxidant outbreaks in Tokyo, these distant sources still make a substantial contribution to exceedance of the Japanese ozone air quality standard in springtime.

  5. Contributions of regional and intercontinental transport to surface ozone in the Tokyo area

    Science.gov (United States)

    Yoshitomi, M.; Wild, O.; Akimoto, H.

    2011-08-01

    Japan lies downwind of the Asian continent and for much of the year air quality is directly influenced by emissions of ozone precursors over these heavily-populated and rapidly-industrializing regions. This study examines the extent to which oxidant transport from regional and distant anthropogenic sources influences air quality in Japan in springtime, when these contributions are largest. We find that European and North American contributions to surface ozone over Japan in spring are persistent, averaging 3.5±1.1 ppb and 2.8±0.5 ppb respectively, and are greatest in cold continental outflow conditions following the passage of cold fronts. Contributions from China are larger, 4.0±2.8 ppb, and more variable, as expected for a closer source region, and are generally highest near cold fronts preceding the influence of more distant sources. The stratosphere provides a varying but ever-present background of ozone of about 11.2±2.5 ppb during spring. Local sources over Japan and Korea have a relatively small impact on mean ozone, 2.4±7.6 ppb, but this masks a strong diurnal signal, and local sources clearly dominate during episodes of high daytime ozone. By examining the meteorological mechanisms that favour transport from different source regions, we demonstrate that while maximum foreign influence generally does not occur at the same time as the greatest buildup of oxidants from local sources, it retains a significant influence under these conditions. It is thus clear that while meteorological boundaries provide some protection from foreign influence during oxidant outbreaks in Tokyo, these distant sources still make a substantial contribution to exceedance of the Japanese ozone air quality standard in springtime.

  6. A Double-Ring Algorithm for Modeling Solar Active Regions: Unifying Kinematic Dynamo Models and Surface Flux-Transport Simulations

    CERN Document Server

    Muñoz-Jaramillo, Andrés; Martens, Petrus C H; Yeates, Anthony R

    2010-01-01

    The emergence of tilted bipolar active regions and the dispersal of their flux, mediated via processes such as diffusion, differential rotation and meridional circulation is believed to be responsible for the reversal of the Sun's polar field. This process (commonly known as the Babcock-Leighton mechanism) is usually modeled as a near-surface, spatially distributed $\\alpha$-effect in kinematic mean-field dynamo models. However, this formulation leads to a relationship between polar field strength and meridional flow speed which is opposite to that suggested by physical insight and predicted by surface flux-transport simulations. With this in mind, we present an improved double-ring algorithm for modeling the Babcock-Leighton mechanism based on active region eruption, within the framework of an axisymmetric dynamo model. Using surface flux-transport simulations we first show that an axisymmetric formulation -- which is usually invoked in kinematic dynamo models -- can reasonably approximate the surface flux dy...

  7. Transport and fate of hexachlorocyclohexanes in the oceanic air and surface seawater

    Directory of Open Access Journals (Sweden)

    Z. Xie

    2011-06-01

    Full Text Available Hexachlorocyclohexanes (HCHs are ubiquitous organic pollutants derived from pesticide application. They are subject to long-range transport, persistent in the environment, and capable of accumulation in biota. Shipboard measurements of HCH isomers (α-, γ- and β-HCH in surface seawater and boundary layer atmospheric samples were conducted in the Atlantic and the Southern Ocean in October to December of 2008. ΣHCHs concentrations (the sum of α-, γ- and β-HCH in the lower atmosphere ranged from 11.8 to 36.9 pg m−3 (mean: 26.6 ± 11.0 pg m−3 in the Northern Hemisphere (NH, and from 1.5 to 4.0 pg m−3 (mean: 2.8 ± 1.1 pg m−3 in the Southern Hemisphere (SH, respectively. Water concentrations were: α-HCH 0.33–46.8 pg l−1, γ-HCH 0.02–33.2 pg l−1 and β-HCH 0.11–2 pg l−1. HCH concentrations decreased from the North Atlantic to the Southern Ocean, indicating historical use of HCHs in the NH. Spatial distribution showed increasing concentrations from the equator towards North and South latitudes illustrating the concept of cold condensation and less interhemispheric mixing process. In comparison to concentrations measured in 1987–1999/2000, gaseous HCHs were slightly lower, while dissolved HCHs decreased by factor of 2–3 orders of magnitude. Air-water exchange gradients suggested net deposition for α-HCH (mean: 3759 pg m−2 day−1 and γ-HCH (mean: 1987 pg m−2 day−1, whereas β-HCH varied between equilibrium (volatilization: <0–12 pg m−2 day−1 and net deposition (range: 6–687 pg m−2 day−1, indicating a multi-hopper transport behavior. Climate change may significantly accelerate the releasing process of "old" HCHs from continental storage (e.g. soil, vegetation and high mountains and drive long-range transport from sources to deposition in the

  8. The effects of surface functionalization on rheology, structure and transport properties of nanocomposites

    Science.gov (United States)

    Ranka, Moulik A.

    In this thesis, the effects of surface functionalization using hydrophobic silanes on properties of nanocomposites comprising 42 nm silica particles suspended in a melt of polyethylene-glycol (PEG) are studied using rheological, static and dynamic x-ray scattering studies. The nanocomposites are studied in the low molecular weight unentangled (PEG-400) and high molecular weight entangled (PEG-20000) regimes. We find no differences in the properties of the bare and silanized particles in the low volume fraction regime up to where the interparticle separation distance h > 6Rg. In the region of 6Rg > h > 3Rg (5Rg > h > 3Rg, in case of entangled melts), we find substantial differences in the rheological, structure and transport properties when comparing the bare and silanized particles. In the unentangled melts, we observe up to four orders of magnitude drop in the viscosity of the composites at the highest levels of silanization and observe shear thinning behavior that is unlike what is universally seen for hard spheres. For the entangled melts, a yield stress is observed for the silanized particles that is absent in the case of the bare particles and there is a divergence in the elastic modulus in comparison to bare particles. We observe an anomalous speed up in the density relaxations and an associated maxima in structure properties in the case of unentangled melts which has been reported previously for particles experiencing soft repulsive potentials. A clear reentrant behavior in structure and transport properties is observed for bare particles in the entangled melts that have been previously reported for particles interacting with soft repulsive potentials such as square shoulder and ramp potentials. In the silanized systems, the density relaxation times although lower than bare particles, is ii unaffected by increasing volume fraction up to h ~ 3Rg and is decoupled from the structure properties which are non-monotonic similar to bare particles. In the region of

  9. Seventh BES (Basic Energy Sciences) catalysis and surface chemistry research conference

    Energy Technology Data Exchange (ETDEWEB)

    1990-03-01

    Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases. (CBS)

  10. Micromechanism of oxygen transport during initial stage oxidation in Si(100) surface: A ReaxFF molecular dynamics simulation study

    Science.gov (United States)

    Sun, Yu; Liu, Yilun; Chen, Xuefeng; Zhai, Zhi; Xu, Fei; Liu, Yijun

    2017-06-01

    The early stage oxidation in Si(100) surface has been investigated in this work by a reactive force field molecular dynamics (ReaxFF MD) simulation, manifesting that the oxygen transport acted as a dominant issue for initial oxidation process. Due to the oxidation, a compressive stress was generated in the oxide layer which blocked the oxygen transport perpendicular to the Si(100) surface and further prevented oxidation in the deeper layer. In contrast, thermal actuation was beneficial to the oxygen transport into deeper layer as temperature increases. Therefore, a competition mechanism was found for the oxygen transport during early stage oxidation in Si(100) surface. At room temperature, the oxygen transport was governed by the blocking effect of compressive stress, so a better quality oxide film with more uniform interface and more stoichiometric oxide structure was obtained. Indeed, the mechanism presented in this work is also applicable for other self-limiting oxidation (e.g. metal oxidation) and is helpful for the design of high-performance electronic devices.

  11. Research on optical measurement for additive manufacturing surfaces

    Science.gov (United States)

    Cheng, Fang; Fu, Shao Wei; Leong, Yong Shin

    2017-02-01

    Surfaces made by Additive Manufacturing (AM) processes normally show higher roughness and more complicated microstructures than conventional machined surfaces. In this study, AM surface roughness measurements using both tactile and optical techniques are analyzed, theoretically and experimentally. Analytical results showed both techniques have comparable performance when measuring AM samples with good surface integrity. For surfaces with steep features, coherence scanning interferometry showed more reliable performance especially when peak-to-valley value was required. In addition of the benchmarking study, development of a low-cost measurement system, using laser confocal technology, is also presented in this paper. By comparing the measurement results with those from a coherent scanning interferometer, accuracy levels of the proposed system can be evaluated. It was concluded that with comparable accuracy, the proposed low-cost optical system was able to achieve much faster measurements, which would make it possible for in-situ surface quality checking.

  12. Research progress on theultra hydrophobic surface topography effect

    Institute of Scientific and Technical Information of China (English)

    WANG Jiadao; YU Ying; CHEN Darong

    2006-01-01

    Ultra hydrophobic surfaces take on better hydrophobicity and exhibit a water contact angle larger than 150°. In this paper the ultra hydrophobicity is analyzed and common fabrication methods are summarized in detail. The applications of micro topography in both the fabrication of hydrophobic surface and the experiments of drag reduction are addressed. Finally, the development trend and foreground of ultra hydrophobic surface are discussed.

  13. Campylobacter fetus surface layer proteins are transported by a type I secretion system.

    Science.gov (United States)

    Thompson, S A; Shedd, O L; Ray, K C; Beins, M H; Jorgensen, J P; Blaser, M J

    1998-12-01

    The virulence of Campylobacter fetus, a bacterial pathogen of ungulates and humans, is mediated in part by the presence of a paracrystalline surface layer (S-layer) that confers serum resistance. The subunits of the S-layer are S-layer proteins (SLPs) that are secreted in the absence of an N-terminal signal sequence and attach to either type A or B C. fetus lipopolysaccharide in a serospecific manner. Antigenic variation of multiple SLPs (encoded by sapA homologs) of type A strain 23D occurs by inversion of a promoter-containing DNA element flanked by two sapA homologs. Cloning and sequencing of the entire 6.2-kb invertible region from C. fetus 23D revealed a probable 5.6-kb operon of four overlapping genes (sapCDEF, with sizes of 1,035, 1,752, 1,284, and 1,302 bp, respectively) transcribed in the opposite direction from sapA. The four genes also were present in the invertible region of type B strain 84-107 and were virtually identical to their counterparts in the type A strain. Although SapC had no database homologies, SapD, SapE, and SapF had predicted amino acid homologies with type I protein secretion systems (typified by Escherichia coli HlyBD/TolC or Erwinia chrysanthemi PrtDEF) that utilize C-terminal secretion signals to mediate the secretion of hemolysins, leukotoxins, or proteases from other bacterial species. Analysis of the C termini of four C. fetus SLPs revealed conserved structures that are potential secretion signals. A C. fetus sapD mutant neither produced nor secreted SLPs. E. coli expressing C. fetus sapA and sapCDEF secreted SapA, indicating that the sapCDEF genes are sufficient for SLP secretion. C. fetus SLPs therefore are transported to the cell surface by a type I secretion system.

  14. Fate and Transport of Nutrients in Groundwater and Surface Water in an Urban Slum Catchment Kampala, Uganda

    NARCIS (Netherlands)

    Nyenje, P.

    2014-01-01

    This study investigates the generation, transport and fate of sanitation-related nutrients in groundwater and surface water in an urban slum area in sub-Saharan Africa. In excess, nutrients can cause eutrophication of downstream water bodies. The study argues that nitrogen-containing rains and

  15. 50 CFR 36.12 - Use of snowmobiles, motorboats, dog teams and other means of surface transportation traditionally...

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Use of snowmobiles, motorboats, dog teams... Subsistence Uses § 36.12 Use of snowmobiles, motorboats, dog teams and other means of surface transportation... provision of subchapter C of title 50 CFR the use of snowmobiles, motorboats, dog teams and other means...

  16. Fate and Transport of Nutrients in Groundwater and Surface Water in an Urban Slum Catchment Kampala, Uganda

    NARCIS (Netherlands)

    Nyenje, P.

    2014-01-01

    This study investigates the generation, transport and fate of sanitation-related nutrients in groundwater and surface water in an urban slum area in sub-Saharan Africa. In excess, nutrients can cause eutrophication of downstream water bodies. The study argues that nitrogen-containing rains and domes

  17. Reactive transport in surface sediments. II. Media: an object-oriented problem-solving environment for early diagenesis

    NARCIS (Netherlands)

    Meysman, F.J.R.; Middelburg, J.J.; Herman, P.M.J.; Heip, C.H.R.

    2003-01-01

    The MEDIA (Modelling Early DIAgenesis) software package comprises a flexible and extensible software system that provides problem-solving assistance for simulating 1D reactive transport in surface sediments. MEDIA allows multiple diagenetic models to be built by extending a model template with new m

  18. Magnetic transport apparatus for the production of ultracold atomic gases in the vicinity of a dielectric surface

    CERN Document Server

    Haendel, S; Wiles, T P; Hopkins, S A; Cornish, S L

    2011-01-01

    We present an apparatus designed for studies of atom-surface interactions using quantum degenerate gases of $^{85}$Rb and $^{87}$Rb in the vicinity of a room temperature dielectric surface. The surface to be investigated is a super-polished face of a glass Dove prism mounted in a glass cell under ultra-high vacuum (UHV). To maintain excellent optical access to the region surrounding the surface magnetic transport is used to deliver ultracold atoms from a separate vacuum chamber housing the magneto-optical trap (MOT). We present a detailed description of the vacuum apparatus highlighting the novel design features; a low profile MOT chamber and the inclusion of an obstacle in the transport path. We report the characterization and optimization of the magnetic transport around the obstacle, achieving transport efficiencies of 70% with negligible heating. Finally we demonstrate the loading of a hybrid optical-magnetic trap with $^{87}$Rb and the creation of Bose-Einstein condensates via forced evaporative cooling ...

  19. Estrogen transport in surface runoff from agricultural fields treated with two different application methods of dairy manure

    Science.gov (United States)

    While the land-application of animal manure provides many benefits, concerns exist regarding the subsequent transport of hormones and potential effects on aquatic ecosystems. This study compares two methods of dairy manure application, surface broadcasting and shallow disk injection, on the fate and...

  20. Stratification, Sediment Transport, and the Early Wet Surface of Meridiani Planum

    Science.gov (United States)

    Grotzinger, J. P.; Athena Science Team

    2004-12-01

    the spectral gap in the size distribution of eolian dunes and ripples. A further clue to the likely subaqueous origin for Eagle cross-laminae is provided by their festoon geometry which requires that the reconstructed ripples have three-dimensional geometry defined by highly sinuous crestlines. In terrestrial settings such bedforms are known only to develop in subaqueous, subcritical flows, with velocities of less than one meter per second. On Mars, the initiation of subaqueous sediment movement is expected to occur at velocities lower than on earth, by a factor of 1.34. With respect to length scales, such as bedform dimensions, the scaling factor turns out to have the opposite sense so that, given dynamically similar flows, ripples on Mars might be larger by a factor of 1.34. Neither of these rescaling effects influences the interpretation that cm-scale, festoon cross-lamination at Eagle crater most probably requires sediment transport in subaqueous, low-velocity flows across the Meridiani plains. The assemblage of primary facies recorded at Eagle crater is most consistent with an environment characterized by episodic inundation by surface water to shallow depths, followed by evaporation, and exposure and desiccation. Terrestrial analogs for such a suite of facies and surface processes include small interdune depressions, playa lakes, and sabkhas adjacent to marginal seaways. All rover observations indicate that the evaporite-bearing cross-bedded unit extends at least on the order of 1 km though MOC and THEMIS data suggest it extends much further.

  1. Upscaling of the specific surface area for reactive transport modelling in fractured rock

    Science.gov (United States)

    Cvetkovic, Vladimir

    2014-05-01

    The impact of flow heterogeneity on chemical transport from single to multiple fractures, is investigated. The emphasis is on the dynamic nature of the specific surface area (SSA) due to heterogeneity of the flow, relative to a purely geometrical definition. It is shown how to account for SSA as a random variable in modelling multi-component reactions. The flow-dependent SSA is interpreted probabilistically, following inert tracer particles along individual fractures. Upscaling to a fracture network is proposed as a time-domain random walk based on the statistics of SSA for single fractures. Statistics of SSA are investigated for three correlation structures of transmissivity, one classical multi-gaussian, and two non-Gaussian. The coefficient of variation of single fracture SSA decreases monotonously with the distance over the fracture length; the CV of the upscaled SSA reduces further such that after ca 20 fractures it is under 0.1 for a disconnected field, and around 0.2 for connected and multi-gaussian fields. This implies that after 10-20 fractures, uncertainty in SSA is significantly reduced, justifying the use of an effective value. A conservative, lower bound for the dimensionless upscaled effective SSA was found to be 1, suitable for all heterogeneity structures, assuming the cubic hydraulic law applicable.

  2. EHD-driven mass transport enhancement in surface dielectric barrier discharges

    Science.gov (United States)

    Taglioli, M.; Shaw, A.; Wright, A.; FitzPatrick, B.; Neretti, G.; Seri, P.; Borghi, C. A.; Iza, F.

    2016-12-01

    Surface dielectric barrier discharges (S-DBDs) have received renewed attention in recent years for their potential application in emerging biomedical, environmental and agricultural applications. In most of these applications, the plasma is not in direct contact with the substrate being treated and the transport of reactive species from the plasma to the substrate is typically assumed to be controlled by diffusion. Here, we demonstrate that generally this is not the case and that electrohydrodynamic (EHD) forces can produce jets that enhance the delivery of these species, thereby influencing the efficacy of the S-DBD device. In particular, we have studied the degradation of potassium indigotrisulfonate solutions exposed to S-DBDs generated in devices with annular electrodes of diameters varying between 10 mm and 50 mm. All the devices were driven at constant linear power density (watts per cm of plasma length) and although local plasma properties remained the same in all the devices, a three-fold efficacy enhancement was observed for devices of diameter ~30 mm due to EHD effects.

  3. A Review of Removable Surface Contamination on Radioactive Materials Transportation Containers

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Jr, W. E.; Watson, E. C.; Murphy, D. W.; Harrer, B. J.; Harty, R.; Aldrich, J. M.

    1981-05-01

    This report contains the results of a study sponsored by the U.S. Nuclear Regulatory Commission (NRC) of removable surface contamination on radioactive materials transportation containers. The purpose of the study is to provide information to the NRC during their review of existing regulations. Data was obtained from both industry and literature on three major topics: 1) radiation doses, 2) economic costs, and 3) contamination frequencies. Containers for four categories of radioactive materials are considered including radiopharmaceuticals, industrial sources, nuclear fuel cycle materials, and low-level radioactive waste. Assumptions made in this study use current information to obtain realistic yet conservative estimates of radiation dose and economic costs. Collective and individual radiation doses are presented for each container category on a per container basis. Total doses, to workers and the public, are also presented for spent fuel cask and low-level waste drum decontamination. Estimates of the additional economic costs incurred by lowering current limits by factors of 10 and 100 are presented. Current contamination levels for each category of container are estimated from the data collected. The information contained in this report is designed to be useful to the NRC in preparing their recommendations for new regulations.

  4. A Versatile Lifting Device for Lunar Surface Payload Handling, Inspection & Regolith Transport Operations

    Science.gov (United States)

    Doggett, William; Dorsey, John; Collins, Tim; King, Bruce; Mikulas, Martin

    2008-01-01

    Devices for lifting and transporting payloads and material are critical for efficient Earth-based construction operations. Devices with similar functionality will be needed to support lunar-outpost construction, servicing, inspection, regolith excavation, grading and payload placement. Past studies have proposed that only a few carefully selected devices are required for a lunar outpost. One particular set of operations involves lifting and manipulating payloads in the 100 kg to 3,000 kg range, which are too large or massive to be handled by unassisted astronauts. This paper will review historical devices used for payload handling in space and on earth to derive a set of desirable features for a device that can be used on planetary surfaces. Next, an innovative concept for a lifting device is introduced, which includes many of the desirable features. The versatility of the device is discussed, including its application to lander unloading, servicing, inspection, regolith excavation and site preparation. Approximate rules, which can be used to size the device for specific payload mass and reach requirements, are provided. Finally, details of a test-bed implementation of the innovative concept, which will be used to validate the structural design and develop operational procedures, is provided.

  5. Surface Evolution of the Sun's Magnetic Field: A Historical Review of the Flux-Transport Mechanism

    Directory of Open Access Journals (Sweden)

    Sheeley Jr. Neil R.

    2005-10-01

    Full Text Available This paper reviews our attempts to understand the transport of magnetic flux on the Sun from the Babcock and Leighton models to the recent revisions that are being used to simulate the field over many sunspot cycles. In these models, the flux originates in sunspot groups and spreads outward on the surface via supergranular diffusion; the expanding patterns become sheared by differential rotation, and the remnants are carried poleward by meridional flow. The net result of all of the flux eruptions during a sunspot cycle is to replace the initial polar fields with new fields of opposite polarity. A central issue in this process is the role of meridional flow, whose relatively low speed is near the limit of detection with Doppler techniques. A compelling feature of Leighton’s original model was that it reversed the polar fields without the need for meridional flow. Now, we think that meridional flow is central to the reversal and to the dynamo itself.

  6. Geocenter motion due to surface mass transport from GRACE satellite data

    Science.gov (United States)

    Riva, R. E. M.; van der Wal, W.; Lavallée, D. A.; Hashemi Farahani, H.; Ditmar, P.

    2012-04-01

    Measurements of mass redistribution from satellite gravimetry are insensitive to geocenter motions. However, geocenter motions can be constrained by satellite gravity data alone if we partition mass changes between land and oceans, under the assumption that the ocean is passive (i.e., in gravitational equilibrium with the land load and the solid earth). Here, we make use of 8 years (2003-2010) of optimally filtered monthly GRACE-based solutions produced at TU Delft to determine changes in the land load and the corresponding geocenter motion, through an iterative procedure. We pay particular attention to correcting for signal leakage caused by the limited spatial resolution of GRACE. We also investigate how the choice of a model of glacial isostatic adjustment (GIA) affects the estimated geocenter motion trend due to present-day surface mass transport. Finally, we separate the contribution of ice masses from that of land hydrology and show how they have a different sensitivity to the chosen GIA model and observational time-span.

  7. Experiment Research on Hot-Rolling Processing of Nonsmooth Pit Surface.

    Science.gov (United States)

    Gu, Yun-Qing; Fan, Tian-Xing; Mou, Jie-Gang; Yu, Wei-Bo; Zhao, Gang; Wang, Evan

    2016-01-01

    In order to achieve the nonsmooth surface drag reduction structure on the inner polymer coating of oil and gas pipelines and improve the efficiency of pipeline transport, a structural model of the machining robot on the pipe inner coating is established. Based on machining robot, an experimental technique is applied to research embossing and coating problems of rolling-head, and then the molding process rules under different conditions of rolling temperatures speeds and depth are analyzed. Also, an orthogonal experiment analysis method is employed to analyze the different effects of hot-rolling process apparatus on the embossed pits morphology and quality of rolling. The results also reveal that elevating the rolling temperature or decreasing the rolling speed can also improve the pit structure replication rates of the polymer coating surface, and the rolling feed has little effect on replication rates. After the rolling-head separates from the polymer coating, phenomenon of rebounding and refluxing of the polymer coating occurs, which is the reason of inability of the process. A continuous hot-rolling method for processing is used in the robot and the hot-rolling process of the processing apparatus is put in a dynamics analysis.

  8. Modeling Np and Pu transport with a surface complexation model and spatially variant sorption capacities: Implications for reactive transport modeling and performance assessments of nuclear waste disposal sites

    Science.gov (United States)

    Glynn, P.D.

    2003-01-01

    One-dimensional (1D) geochemical transport modeling is used to demonstrate the effects of speciation and sorption reactions on the ground-water transport of Np and Pu, two redox-sensitive elements. Earlier 1D simulations (Reardon, 1981) considered the kinetically limited dissolution of calcite and its effect on ion-exchange reactions (involving 90Sr, Ca, Na, Mg and K), and documented the spatial variation of a 90Sr partition coefficient under both transient and steady-state chemical conditions. In contrast, the simulations presented here assume local equilibrium for all reactions, and consider sorption on constant potential, rather than constant charge, surfaces. Reardon's (1981) seminal findings on the spatial and temporal variability of partitioning (of 90Sr) are reexamined and found partially caused by his assumption of a kinetically limited reaction. In the present work, sorption is assumed the predominant retardation process controlling Pu and Np transport, and is simulated using a diffuse-double-layer-surface-complexation (DDLSC) model. Transport simulations consider the infiltration of Np- and Pu-contaminated waters into an initially uncontaminated environment, followed by the cleanup of the resultant contamination with uncontaminated water. Simulations are conducted using different spatial distributions of sorption capacities (with the same total potential sorption capacity, but with different variances and spatial correlation structures). Results obtained differ markedly from those that would be obtained in transport simulations using constant Kd, Langmuir or Freundlich sorption models. When possible, simulation results (breakthrough curves) are fitted to a constant K d advection-dispersion transport model and compared. Functional differences often are great enough that they prevent a meaningful fit of the simulation results with a constant K d (or even a Langmuir or Freundlich) model, even in the case of Np, a weakly sorbed radionuclide under the

  9. Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

    Science.gov (United States)

    Walker, R. D., Jr.

    1973-01-01

    Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

  10. Relating a Jet-Surface Interaction Experiment to a Commercial Supersonic Transport Aircraft Using Numerical Simulations

    Science.gov (United States)

    Dippold, Vance F. III; Friedlander, David

    2017-01-01

    Reynolds-Averaged Navier-Stokes (RANS) simulations were performed for a commercial supersonic transport aircraft concept and experimental hardware models designed to represent the installed propulsion system of the conceptual aircraft in an upcoming test campaign. The purpose of the experiment is to determine the effects of jet-surface interactions from supersonic aircraft on airport community noise. RANS simulations of the commercial supersonic transport aircraft concept were performed to relate the representative experimental hardware to the actual aircraft. RANS screening simulations were performed on the proposed test hardware to verify that it would be free from potential rig noise and to predict the aerodynamic forces on the model hardware to assist with structural design. The simulations showed a large region of separated flow formed in a junction region of one of the experimental configurations. This was dissimilar with simulations of the aircraft and could invalidate the noise measurements. This configuration was modified and a subsequent RANS simulation showed that the size of the flow separation was greatly reduced. The aerodynamic forces found on the experimental models were found to be relatively small when compared to the expected loads from the model’s own weight.Reynolds-Averaged Navier-Stokes (RANS) simulations were completed for two configurations of a three-stream inverted velocity profile (IVP) nozzle and a baseline single-stream round nozzle (mixed-flow equivalent conditions). For the Sideline and Cutback flow conditions, while the IVP nozzles did not reduce the peak turbulent kinetic energy on the lower side of the jet plume, the IVP nozzles did significantly reduce the size of the region of peak turbulent kinetic energy when compared to the jet plume of the baseline nozzle cases. The IVP nozzle at Sideline conditions did suffer a region of separated flow from the inner stream nozzle splitter that did produce an intense, but small, region of

  11. Impact of storm-induced cooling of sea surface temperature on large turbulent eddies and vertical turbulent transport in the atmospheric boundary layer of Hurricane Isaac

    Science.gov (United States)

    Zhu, Ping; Wang, Yuting; Chen, Shuyi S.; Curcic, Milan; Gao, Cen

    2016-01-01

    Roll vortices in the atmospheric boundary layer (ABL) are important to oil operation and oil spill transport. This study investigates the impact of storm-induced sea surface temperature (SST) cooling on the roll vortices generated by the convective and dynamic instability in the ABL of Hurricane Isaac (2012) and the roll induced transport using hindcasting large eddy simulations (LESs) configured from the multiply nested Weather Research & Forecasting model. Two experiments are performed: one forced by the Unified Wave INterface - Coupled Model and the other with the SST replaced by the NCEP FNL analysis that does not include the storm-induced SST cooling. The simulations show that the roll vortices are the prevalent eddy circulations in the ABL of Isaac. The storm-induced SST cooling causes the ABL stability falls in a range that satisfies the empirical criterion of roll generation by dynamic instability, whereas the ABL stability without considering the storm-induced SST cooling meets the criterion of roll generation by convective instability. The ABL roll is skewed and the increase of convective instability enhances the skewness. Large convective instability leads to large vertical transport of heat and moisture; whereas the dominant dynamic instability results in large turbulent kinetic energy but relatively weak heat and moisture transport. This study suggests that failure to consider roll vortices or incorrect initiation of dynamic and convective instability of rolls in simulations may substantially affect the transport of momentum, energy, and pollutants in the ABL and the dispersion/advection of oil spill fume at the ocean surface.

  12. Research on Ultrasonic NDT System for Complex Surface Parts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Aimed at inner quality controlling for complex surface parts, an ultrasonic testing system for complex surface parts has been developed using ultrasonic NDT(Non-destructive Testing)which has features of strong penetration, well direction, high sensitivity, low cost, and harmless to people and material. The technologies of the computer, NC (Numerical control), precision mechanism, signal analysis and processing were integrated in the testing system. The system includes a PC, system software, ultrasonic data ...

  13. The Conference Proceedings of the 2003 Air Transport Research Society (ATRS) World Conference, Volume 5

    Science.gov (United States)

    Bowen, Brent (Editor); Gudmundsson, Sveinn (Editor); Oum, Tae (Editor)

    2003-01-01

    The UNO Aviation Institute Monograph Series began in 1994 as a key component of the education outreach and information transfer missions of the Aviation Institute and the NASA Nebraska Space Grant & EPSCoR Programs. The series is an outlet for aviation materials to be indexed and disseminated through an efficient medium. Publications are welcome in all aspects of aviation. Publication formats may include, but are not limited to, conference proceedings, bibliographies, research reports, manuals, technical reports, and other documents that should be archived and indexed for future reference by the aviation and world wide communities. The Conference proceedings of the 2003 Air Transport Research Society (ATRS) world conference, volume 5 is presented. The topics include: 1) The Temporal Configuration of Airline Networks in Europe; 2) Determination and Applications of Environmental Costs at Different Sized Airports-Aircraft Noise and Engine Emissions; 3) Cost Effective Measures to Reduce CO2 Emissions in the Air Freight Sector; 4) An Assessment of the Sustainability of Air Transport System: Quantification of Indicators; 5) Regulation, Competition and Network Evolution in Aviation; 6) Regulation in the Air: Price and Frequency Cap; 7) Industry Consolidation and Future Airline Network Structures in Europe; 8) Application of Core Theory to the U.S. Airline Industry; 9) Air Freight Transshipment Route Choice Analysis; 10) A Fuzzy Approach of the Competition on Air Transport Market; and 11) Developing Passenger Demand Models for International Aviation from/to Egypt: A Case Study of Cairo Airport and Egyptair.

  14. Research of transport and deposition of aerosol in human airway replica

    Directory of Open Access Journals (Sweden)

    Mravec Filip

    2012-04-01

    Full Text Available Growing concern about knowledge of aerosol transport in human lungs is caused by great potential of use of inhaled pharmaceuticals. Second substantial motive for the research is an effort to minimize adverse effects of particular matter emitted by traffic and industry on human health. We created model geometry of human lungs to 7th generation of branching. This model geometry was used for fabrication of two physical models. The first one is made from thin walled transparent silicone and it allows a measurement of velocity and size of aerosol particles by Phase Doppler Anemometry (PDA. The second one is fabricated by stereolithographic method and it is designed for aerosol deposition measurements. We provided a series of measurements of aerosol transport in the transparent model and we ascertained remarkable phenomena linked with lung flow. The results are presented in brief. To gather how this phenomena affects aerosol deposition in human lungs we used the second model and we developed a technique for deposition fraction and deposition efficiency assessment. The results confirmed that non-symmetric and complicated shape of human airways essentially affects transport and deposition of aerosol. The research will now focus on deeper insight in aerosol deposition.

  15. GPS based surface displacements – a proxy for discharge and sediment transport from the Greenland Ice Sheet

    Directory of Open Access Journals (Sweden)

    B. Hasholt

    2014-07-01

    Full Text Available The elastic respond of the Earth's surface to mass changes has been measured with Global Positioning System (GPS. Mass loss as accumulated runoff and sediment transport from a 10 000 km2 segment of the Greenland Ice Sheet (GrIS correlated very well (R2 = 0.83 with GPS measured uplift. Accumulated winter precipitation correlated fairly well with surface depression (R2 = 0.69. The relationships are based on seven years of runoff and sediment transport observations from the Watson River (2007–2013, winter precipitation from Kangerlussuaq Airport and GPS observations at Kellyville. GPS recordings of surface subsidence and uplift from 1996–2013 are used to calculate 18 years time series of annual runoff, sediment and solute transport and winter precipitation. Runoff and related transport of sediment and solutes increase over the period, while winter precipitation (land depression tends to decrease. Based on the entire GPS record (1996–2013, it is shown that until 2005–2006 the mass balance of this segment of the GrIS was rather stable – since then there has been an increasing loss of mass, culminating in 2012.

  16. Progress in Understanding Land-Surface-Atmosphere Coupling from LBA Research

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2010-06-01

    Full Text Available LBA research has deepened our understanding of the role of soil water storage, clouds and aerosols in land-atmosphere coupling. We show how the reformulation of cloud forcing in terms of an effective cloud albedo per unit area of surface gives a useful measure of the role of clouds in the surface energy budget over the Amazon. We show that the diurnal temperature range has a quasi-linear relation to the daily mean longwave cooling; and to effective cloud albedo because of the tight coupling between the near-surface climate, the boundary layer and the cloud field. The coupling of surface and atmospheric processes is critical to the seasonal cycle: deep forest rooting systems make water available throughout the year, whereas in the dry season the shortwave cloud forcing is reduced by regional scale subsidence, so that more light is available for photosynthesis. At sites with an annual precipitation above 1900 mm and a dry season length less than 4 months, evaporation rates increased in the dry season, coincident with increased radiation. In contrast, ecosystems with precipitation less than 1700 mm and a longer dry season showed clear evidence of reduced evaporation in the dry season coming from water stress. In all these sites, the seasonal variation of the effective cloud albedo is a major factor in determining the surface available energy. Dry season fires add substantial aerosol to the atmosphere. Aerosol scattering and absorption both reduce the total downward surface radiative flux, but increase the diffuse/direct flux ratio, which increases photosynthetic efficiency. Convective plumes produced by fires enhance the vertical transport of aerosols over the Amazon, and effectively inject smoke aerosol and gases directly into the middle troposphere with substantial impacts on mid- tropospheric dispersion. In the rainy season in Rondônia, convection in low-level westerly flows with low aerosol content resembles oceanic convection with

  17. Clay mineral distribution in surface sediments of the South China Sea and its significance for in sediment sources and transport

    Institute of Scientific and Technical Information of China (English)

    刘建国; 陈木宏; 陈忠; 颜文

    2010-01-01

    Clay minerals of surface sediments in the South China Sea (SCS) are analyzed with X-ray diffraction, and their transport is explored with a grain size trend analysis (GSTA) model. Results show that clay mineral types in various sedimentary environments have different sediment sources and transport routes. Sediments in the northern SCS (north of 20°N) between the southwest of Taiwan Island and the outer mouth of the Pearl River have high contents of illite and chlorite, which are derived mainly from sediment...

  18. A non-equilibrium model for soil heating and moisture transport during extreme surface heating

    Directory of Open Access Journals (Sweden)

    W. J. Massman

    2015-03-01

    Full Text Available With increasing use of prescribed fire by land managers and increasing likelihood of wildfires due to climate change comes the need to improve modeling capability of extreme heating of soils during fires. This issue is addressed here by developing a one-dimensional non-equilibrium model of soil evaporation and transport of heat, soil moisture, and water vapor, for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. The model employs a linearized Crank–Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m−2. The Hertz–Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. The model includes a dynamic residual soil moisture as a function of temperature and soil water potential, which allows the model to capture some of the dynamic aspects of the strongly bound soil moisture that seems to require temperatures well beyond 150 °C to fully evaporate. Furthermore, the model emulates the observed increase in soil moisture ahead of the drying front and the hiatus in the soil temperature rise during the strongly evaporative stage of drying. It also captures the observed rapid evaporation of soil moisture that occurs at relatively low temperatures (50–90 °C. Sensitivity analyses indicate that the model's success results primarily from the use of a temperature and moisture potential dependent condensation coefficient in the evaporative source term. The model's solution for water vapor density (and vapor pressure, which can exceed one standard atmosphere, cannot be experimentally verified, but they are supported by results from (earlier and very different models developed for somewhat different purposes and for different porous

  19. Biomimetic Bacterial Identification Platform Based on Thermal Wave Transport Analysis (TWTA) through Surface-Imprinted Polymers.

    Science.gov (United States)

    Steen Redeker, Erik; Eersels, Kasper; Akkermans, Onno; Royakkers, Jeroen; Dyson, Simba; Nurekeyeva, Kunya; Ferrando, Beniamino; Cornelis, Peter; Peeters, Marloes; Wagner, Patrick; Diliën, Hanne; van Grinsven, Bart; Cleij, Thomas Jan

    2017-05-12

    This paper introduces a novel bacterial identification assay based on thermal wave analysis through surface-imprinted polymers (SIPs). Aluminum chips are coated with SIPs, serving as synthetic cell receptors that have been combined previously with the heat-transfer method (HTM) for the selective detection of bacteria. In this work, the concept of bacterial identification is extended toward the detection of nine different bacterial species. In addition, a novel sensing approach, thermal wave transport analysis (TWTA), is introduced, which analyzes the propagation of a thermal wave through a functional interface. The results presented here demonstrate that bacterial rebinding to the SIP layer resulted in a measurable phase shift in the propagated wave, which is most pronounced at a frequency of 0.03 Hz. In this way, the sensor is able to selectively distinguish between the different bacterial species used in this study. Furthermore, a dose-response curve was constructed to determine a limit of detection of 1 × 10(4) CFU mL(-1), indicating that TWTA is advantageous over HTM in terms of sensitivity and response time. Additionally, the limit of selectivity of the sensor was tested in a mixed bacterial solution, containing the target species in the presence of a 99-fold excess of competitor species. Finally, a first application for the sensor in terms of infection diagnosis is presented, revealing that the platform is able to detect bacteria in clinically relevant concentrations as low as 3 × 10(4) CFU mL(-1) in spiked urine samples.

  20. The solenoidal transport option: IFE drivers, near term research facilities, and beam dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, E.P. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States); Briggs, R.J. [Science Applications International Corp., Pleasanton, CA (United States)

    1997-09-01

    Solenoidal magnets have been used as the beam transport system in all the high current electron induction accelerators that have been built in the past several decades. They have also been considered for the front end transport system for heavy ion accelerators for Inertial Fusion Energy (IFE) drivers, but this option has received very little attention in recent years. The analysis reported here was stimulated mainly by the recent effort to define an affordable {open_quotes}Integrated Research Experiment{close_quotes} (IRE) that can meet the near term needs of the IFE program. The 1996 FESAC IFE review panel agreed that an integrated experiment is needed to fully resolve IFE heavy ion driver science and technology issues; specifically, {open_quotes}the basic beam dynamics issues in the accelerator, the final focusing and transport issues in a reactor-relevant beam parameter regime, and the target heating phenomenology{close_quotes}. The development of concepts that can meet these technical objectives and still stay within the severe cost constraints all new fusion proposals will encounter is a formidable challenge. Solenoidal transport has a very favorable scaling as the particle mass is decreased (the main reason why it is preferred for electrons in the region below 50 MeV). This was recognized in a recent conceptual study of high intensity induction linac-based proton accelerators for Accelerator Driven Transmutation Technologies, where solenoidal transport was chosen for the front end. Reducing the ion mass is an obvious scaling to exploit in an IRE design, since the output beam voltage will necessarily be much lower than that of a full scale driver, so solenoids should certainly be considered as one option for this experiment as well.

  1. Surface modification on silicon with chitosan and biological research

    Energy Technology Data Exchange (ETDEWEB)

    Lue Xiaoying; Cui Wei; Huang Yan; Zhao Yi [State Key Laboratory of Bioelectronics, Southeast University, Nanjing, 210096 (China); Wang Zhigong, E-mail: luxy@seu.edu.c [Institute of RF- and OE-ICs, Southeast University, Nanjing, 210096 (China)

    2009-08-15

    The aim of the present study was to investigate the effect of chitosan modification of silicon (Si) on protein adsorption, cell adhesion and cell proliferation. Chitosan was first immobilized on the Si surface through a (3-aminopropyl)triethoxysilane (APTES) bridge. The surface was then characterized by contact angle measurement, atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectroscopy (EDX). The amount of protein adsorbed on the native Si and chitosan-modified Si surface was evaluated by a modified Coomassie brilliant blue (CBB) protein assay. The adhesion and proliferation behavior of L-929 and pc12 cells were then assessed by microscopy and methylthiazoltetrazolium (MTT) tests. The results showed that the chitosan modification could resist protein adsorption and inhibit the adhesion and proliferation of two kinds of cells on Si.

  2. Kinesin-5/Eg5 is important for transport of CARTS from the trans-Golgi network to the cell surface

    Science.gov (United States)

    Villeneuve, Julien; van Galen, Josse; Cruz-Garcia, David; Tagaya, Mitsuo

    2013-01-01

    Here we report that the kinesin-5 motor Klp61F, which is known for its role in bipolar spindle formation in mitosis, is required for protein transport from the Golgi complex to the cell surface in Drosophila S2 cells. Disrupting the function of its mammalian orthologue, Eg5, in HeLa cells inhibited secretion of a protein called pancreatic adenocarcinoma up-regulated factor (PAUF) but, surprisingly, not the trafficking of vesicular stomatitis virus G protein (VSV-G) to the cell surface. We have previously reported that PAUF is transported from the trans-Golgi network (TGN) to the cell surface in specific carriers called CARTS that exclude VSV-G. Inhibition of Eg5 function did not affect the biogenesis of CARTS; however, their migration was delayed and they accumulated near the Golgi complex. Altogether, our findings reveal a surprising new role of Eg5 in nonmitotic cells in the facilitation of the transport of specific carriers, CARTS, from the TGN to the cell surface. PMID:23857769

  3. Research of some marks contemporary hydrocarbon fuel surface tension

    Directory of Open Access Journals (Sweden)

    С.В. Бойченко

    2005-01-01

    Full Text Available  The  surface  tension  of  some  marks  domestic  and  foreign  gasoline’s  and  jet  fuels  is  investigated  depending  on  distillation. Dependences  of  surface  tension,  composition,  boiling  points  liquid  fuel  experimentally  are  received.

  4. Experimental research of surface roughness and surface texture after laser cladding

    Science.gov (United States)

    Przestacki, Damian; Majchrowski, Radomir; Marciniak-Podsadna, Lidia

    2016-12-01

    The objective of the investigation was to identify surface integrity of machined parts after laser cladding. Surface analysis was made by using novel metrology methods: auto correlation and gradient distributions. An Infinite Focus Measurement Machine (IFM) has been used for the surface texture analysis. The study has been performed within a production facility during the prototyping process of new products. There are many methods available for geometric and surface topography measurements: contact and non-contact, micro and nanoscale approaches. An optical method based on the measurement of light reflected or scattered from the surface of an examined object can be used for this purpose. We have tested the application of an advanced 3D scanner for this purpose - optical scanner ATOS II. The scanner ATOS II represents the optical method, i.e. the digital light projection (DLP) method. The system consists of a projector and two digital cameras capable of supplying 1.4 million of measuring points per second. This method enables to scan elements from a few millimeters to a several dozen of meters in size. The roughness analysis is based on 2D measurements, which gave two-dimensional characteristics of the surface. In last decades, the metrology of the surface layer notes dynamical development as a science. During the last decades, many scientists and constructors became convinced that the third dimension should be added to the surface analysis. At present, 3D analysis of the surface geometry is widely accepted. In order to complete the topography analysis of the surface texture after laser cladding, our team worked out original program for 2D and 3D surface analysis. It was called TAS (topography analysis and simulation) and was based on Matlab software. Four modules were developed: the initial data processing module, basic parameters calculating module, data visualization module, and digital filtration module.

  5. Surface electronic transport measurements: A micro multi-point probe approach

    DEFF Research Database (Denmark)

    Barreto, Lucas

    2014-01-01

    This work is mostly focused on the study of electronic transport properties of two-dimensional materials, in particular graphene and topological insulators. To study these, we have improved a unique micro multi-point probe instrument used to perform transport measurements. Not only the experimental...

  6. Transport of temperature and humidity variance and covariance in the marine surface layer

    DEFF Research Database (Denmark)

    Sempreviva, A.M.; Højstrup, J.

    1998-01-01

    In this paper we address the budget of potential temperature T and moisture mixing ratio q variances as well as the q - T covariance budget. We focus on the vertical transport and study the quantities contained in these terms. Estimates of transport terms are rare and to the best of our knowledge...

  7. An overview of the 2013 Las Vegas Ozone Study (LVOS): Impact of stratospheric intrusions and long-range transport on surface air quality

    Science.gov (United States)

    Langford, A. O.; Senff, C. J.; Alvarez, R. J.; Brioude, J.; Cooper, O. R.; Holloway, J. S.; Lin, M. Y.; Marchbanks, R. D.; Pierce, R. B.; Sandberg, S. P.; Weickmann, A. M.; Williams, E. J.

    2015-05-01

    The 2013 Las Vegas Ozone Study (LVOS) was conducted in the late spring and early summer of 2013 to assess the seasonal contribution of stratosphere-to-troposphere transport (STT) and long-range transport to surface ozone in Clark County, Nevada and determine if these processes directly contribute to exceedances of the National Ambient Air Quality Standard (NAAQS) in this area. Secondary goals included the characterization of local ozone production, regional transport from the Los Angeles Basin, and impacts from wildfires. The LVOS measurement campaign took place at a former U.S. Air Force radar station ∼45 km northwest of Las Vegas on Angel Peak (∼2.7 km above mean sea level, asl) in the Spring Mountains. The study consisted of two extended periods (May 19-June 4 and June 22-28, 2013) with near daily 5-min averaged lidar measurements of ozone and backscatter profiles from the surface to ∼2.5 km above ground level (∼5.2 km asl), and continuous in situ measurements (May 20-June 28) of O3, CO, (1-min) and meteorological parameters (5-min) at the surface. These activities were guided by forecasts and analyses from the FLEXPART (FLEXible PARTticle) dispersion model and the Real Time Air Quality Modeling System (RAQMS), and the NOAA Geophysical Research Laboratory (NOAA GFDL) AM3 chemistry-climate model. In this paper, we describe the LVOS measurements and present an overview of the results. The combined measurements and model analyses show that STT directly contributed to each of the three O3 exceedances that occurred in Clark County during LVOS, with contributions to 8-h surface concentrations in excess of 30 ppbv on each of these days. The analyses show that long-range transport from Asia made smaller contributions (<10 ppbv) to surface O3 during two of those exceedances. The contribution of regional wildfires to surface O3 during the three LVOS exceedance events was found to be negligible, but wildfires were found to be a major factor during exceedance events

  8. IASOA circumpolar observations in service for research of atmospheric transports into and out of the Arctic

    Science.gov (United States)

    Vihma, Timo; Uttal, Taneil; Walden, Von; Cox, Christopher; Starkweather, Sandy; Makshtas, Alexander; Key, Jeff

    2016-04-01

    The International Arctic Systems for Observing the Atmosphere (IASOA) is an International Polar Year legacy consortium that focuses on coordinating measurements of the Arctic atmosphere collected at ten observatories in the U.S., Canada, Russia, Norway, Finland, and Greenland. The IASOA data portal and collaboratory process support thematic expert groups that work towards common goals for utilizing interoperable data products across the observatories. In addition to detailed surface observations and upper-air radiosonde program, some of the IASOA observatories collect information on the vertical profiles of moisture, cloud boundaries, cloud water/ice contents, and aerosols using radars, lidars ceilometers and radiometers. Collectively the IASOA network provides a unique source of information that can be utilized in order to provide the best possible empirical estimates of the horizontal atmospheric transports of momentum, heat, moisture, cloud water, cloud ice, and aerosols into and out of the Arctic Ocean region. These can be used in turn to support the evaluation of atmospheric reanalyses, weather and climate models, and satellite remote sensing products, and subsequently studies on the interaction between the Arctic and lower latitudes including the role of mid- and low-latitude forcing on the Arctic amplification of climate warming and the effects of Arctic changes on mid-latitude weather and climate. In addition, the IASOA data are valuable for the evaluation of gridded products (reanalyses, models, and satellite data) with respect to Earth surface variables, such as snow depth, soil moisture, surface temperature, radiative fluxes, albedo, as well as turbulent fluxes of sensible heat, latent heat, CO2, and CH4. Evaluation of surface fluxes is a vital to complement the evaluation of horizontal transports. These together will yield a comprehensive assessment of the quality of available gridded products in representing atmospheric budgets of heat, moisture

  9. Frontiers in transport phenomena research and education: Energy systems, biological systems, security, information technology and nanotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, T.L.; Faghri, A. [Department of Mechanical Engineering, The University of Connecticut, Storrs, CT 06269-3139 (United States); Viskanta, R. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088 (United States)

    2008-09-15

    A US National Science Foundation-sponsored workshop entitled ''Frontiers in Transport Phenomena Research and Education: Energy Systems, Biological Systems, Security, Information Technology, and Nanotechnology'' was held in May of 2007 at the University of Connecticut. The workshop provided a venue for researchers, educators and policy-makers to identify frontier challenges and associated opportunities in heat and mass transfer. Approximately 300 invited participants from academia, business and government from the US and abroad attended. Based upon the final recommendations on the topical matter of the workshop, several trends become apparent. A strong interest in sustainable energy is evident. A continued need to understand the coupling between broad length (and time) scales persists, but the emerging need to better understand transport phenomena at the macro/mega scale has evolved. The need to develop new metrology techniques to collect and archive reliable property data persists. Societal sustainability received major attention in two of the reports. Matters involving innovation, entrepreneurship, and globalization of the engineering profession have emerged, and the responsibility to improve the technical literacy of the public-at-large is discussed. Integration of research thrusts and education activities is highlighted throughout. Specific recommendations, made by the panelists with input from the international heat transfer community and directed to the National Science Foundation, are included in several reports. (author)

  10. Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters

    Science.gov (United States)

    Nordstrom, D. Kirk

    2011-01-01

    The formation of acid mine drainage from metals extraction or natural acid rock drainage and its mixing with surface waters is a complex process that depends on petrology and mineralogy, structural geology, geomorphology, surface-water hydrology, hydrogeology, climatology, microbiology, chemistry, and mining and mineral processing history. The concentrations of metals, metalloids, acidity, alkalinity, Cl-, F- and SO42- found in receiving streams, rivers, and lakes are affected by all of these factors and their interactions. Remediation of mine sites is an engineering concern but to design a remediation plan without understanding the hydrogeochemical processes of contaminant mobilization can lead to ineffective and excessively costly remediation. Furthermore, remediation needs a goal commensurate with natural background conditions rather than water-quality standards that might bear little relation to conditions of a highly mineralized terrain. This paper reviews hydrogeochemical generalizations, primarily from US Geological Survey research, that enhance our understanding of the origin, transport, and fate of contaminants released from mined and mineralized areas.

  11. On the Sensitivity of Atmospheric Model Implied Ocean Heat Transport to the Dominant Terms of the Surface Energy Balance

    Energy Technology Data Exchange (ETDEWEB)

    Gleckler, P J

    2004-11-03

    The oceanic meridional heat transport (T{sub o}) implied by an atmospheric General Circulation Model (GCM) can help evaluate a model's readiness for coupling with an ocean GCM. In this study we examine the T{sub o} from benchmark experiments of the Atmospheric Model Intercomparison Project, and evaluate the sensitivity of T{sub o} to the dominant terms of the surface energy balance. The implied global ocean TO in the Southern Hemisphere of many models is equatorward, contrary to most observationally-based estimates. By constructing a hybrid (model corrected by observations) T{sub o}, an earlier study demonstrated that the implied heat transport is critically sensitive to the simulated shortwave cloud radiative effects, which have been argued to be principally responsible for the Southern Hemisphere problem. Systematic evaluation of one model in a later study suggested that the implied T{sub o} could be equally as sensitive to a model's ocean surface latent heat flux. In this study we revisit the problem with more recent simulations, making use of estimates of ocean surface fluxes to construct two additional hybrid calculations. The results of the present study demonstrate that indeed the implied T{sub o} of an atmospheric model is very sensitive to problems in not only the surface net shortwave, but the latent heat flux as well. Many models underestimate the shortwave radiation reaching the surface in the low latitudes, and overestimate the latent heat flux in the same region. The additional hybrid transport calculations introduced here could become useful model diagnostic tests as estimates of implied ocean surface fluxes are improved.

  12. Accurate testing of aspheric surfaces using the transport of intensity equation by properly selecting the defocusing distance.

    Science.gov (United States)

    Soltani, Peyman; Darudi, Ahmad; Nehmetallah, George; Moradi, Ali Reza; Amiri, Javad

    2016-12-10

    In the last decade, the transport of intensity has been increasingly used in microscopy, wavefront sensing, and metrology. In this study, we verify by simulation and experiment the use of the transport of intensity equation (TIE) in the accurate testing of optical aspheric surfaces. Guided by simulation results and assuming that the experimental setup parameters and the conic constants are known, one can estimate an appropriate defocusing distance Δz that leads to an accurate solution of the TIE. In this paper, this method is verified through the construction of a non-nulled experiment for testing the 2D profile of an aspheric surface. The theoretical method and experimental results are compared to validate the results. Finally, to validate the TIE methodology, the phase distribution obtained by TIE is compared with the phase distribution obtained by a Shack-Hartmann sensor.

  13. A biogeochemical transport model to simulate the attenuation of chlorinated hydrocarbon contaminant fluxes across the groundwater-surface water interface

    DEFF Research Database (Denmark)

    Malaguerra, Flavio; Binning, Philip John; Albrechtsen, Hans-Jørgen

    2009-01-01

    Chlorinated hydrocarbons originating from point sources are amongst the most prevalent contaminants of ground water and surface water resources. Riparian zones may play an important role in the attenuation of contaminant concentrations when contaminant plumes flow from groundwater to surface water...... because of the occurrence of redox gradients, strongly reductive conditions and high biological activity. In order to meet the expectations of the EU Water Framework Directive, an evaluation of the impact of such plumes on surface water is needed. The aim of this work is to develop a groundwater transport...... number of geochemical processes, allows the simulation of soil geochemical transformations when microbial by-products are released to surface water, and the consideration of non-linear feedbacks on bacterial growth and pollutant transformations. Sensitivity analysis is performed through Monte Carlo...

  14. Effect of bulk charged impurities on the bulk and surface transport in three-dimensional topological insulators

    OpenAIRE

    2013-01-01

    In the three-dimensional topological insulator (TI), the physics of doped semiconductors exists literally side-by-side with the physics of ultra-relativistic Dirac fermions. This unusual pairing creates a novel playground for studying the interplay between disorder and electronic transport. In this mini-review we focus on the disorder caused by the three-dimensionally distributed charged impurities that are ubiquitous in TIs, and we outline the effects it has on both the bulk and surface tran...

  15. Control of start-up and dynamic braking of conveyors used for downhill transport in surface mines

    Energy Technology Data Exchange (ETDEWEB)

    Rosseger, A.; Borczyk, Z.; Kwater, M. (POLTEGOR Instytut, Wroclaw (Poland))

    1992-04-01

    Presents the structure of a microprocessor-aided control system for conveyors used in surface mines for downhill transport. Control of motor start-up and braking is performed in 8 speed stages. Permissible starting time duration is taken into consideration. The procedure of direct current braking is described. The microprocessor activates emergency braking by disc brakes if direct current braking is not sufficient. The system was implemented on four conveyors and has been used successfully since 1990.

  16. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B.

    Science.gov (United States)

    Meng, Yan; Zhao, Chunyan; Zhang, Xuexin; Zhao, Huashan; Guo, Lirong; Lü, Bin; Zhao, Xuejian; Yang, Baoxue

    2009-05-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead II) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by floating microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5 +/- 4.2), (45.5 +/- 6.9) and (43.8 +/- 7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6 +/- 2.9), (38.7 +/- 5.6) and (38.2 +/- 7.3) ms, PUT-B null mice (52 w old). The amplitude of action potential and V (max) decreased significantly in UT-B null mice ((92.17 +/- 10.56) and (101.89 +/- 9.54) mV/s) vs those in wild-type mice (vs (110.51 +/- 10.38) and (109.53 +/- 10.64) mV/s, PUT-B null mice ((123.83 +/- 11.17) and (195.43 +/- 16.41) ms) vs that in wild-type mice ((108.27 +/- 10.85) and (171.00 +/- 15.53) ms, PUT-B null mice (-8.80 +/- 0.92) nA vs that in wild-type mice ((-5.98 +/- 1.07) nA, PUT-B deletion causes progressive heart block in mice.

  17. A review of rapid transport of pesticides from sloping farmland to surface waters: Processes and mitigation strategies

    Institute of Scientific and Technical Information of China (English)

    Xiangyu Tang; Bo Zhu; Hidetaka Katou

    2012-01-01

    Pesticides applied to sloping farmland may lead to surface water contamination through rapid transport processes as influenced by the complex topography and high spatial variability of soil properties and land use in hilly or mountainous regions.However,the fate of pesticides applied to sloping farmland has not been sufficiently elucidated.This article reviews the current understanding of pesticide transport from sloping farmland to surface water.It examines overland flow and subsurface lateral flow in areas where surface soil is underlain by impervious subsoil or rocks and tile drains.It stresses the importance of quantifying and modeling the contributions of various pathways to rapid pesticide loss at catchment and regional scales.Such models could be used in scenario studies for evaluating the effectiveness of possible mitigation strategies such as constructing vegetated strips,depressions,wetlands and drainage ditches,and implementing good agricultural practices.Field monitoring studies should also be conducted to calibrate and validate the transport models as well as biophysical-economic models,to optimize mitigation measures in areas dominated by sloping farmland.

  18. In Situ Determination of the Transport Properties of Near-Surface Concrete Using AC Impedance Spectroscopy Techniques

    Directory of Open Access Journals (Sweden)

    Lipeng Wu

    2016-01-01

    Full Text Available The durability of existing concrete structures has increasingly attracted widespread attention in recent years. The phenomenon of performance degradation is often associated with the intrusion of hazardous ions from outside. As the first barrier to external substances intrusion, the near-surface concrete plays an important role in durability. So the performance of in-service concrete structures often depends on the transport properties of the near-surface concrete. Accordingly, information on service conditions and life prediction can be obtained by testing these transport properties. In this paper, an in situ method for chloride ion diffusion coefficient determination is proposed based on the relationship between the alternating current impedance spectroscopy parameters and the chloride ion diffusion coefficient. By a rational design, the new method can synthetically reflect the transport properties of near-surface concrete and is not affected by the presence of the reinforcing bar. In addition, the experimental results show that the method is in good agreement with “PERMIT” migration test which has been widely used. The proposed method is less time consuming and nondestructive and has good reproducibility.

  19. Redistribution of monocarboxylate transporter 2 on the surface of astrocytes in the human epileptogenic hippocampus

    DEFF Research Database (Denmark)

    Lauritzen, Fredrik; Heuser, Kjell; de Lanerolle, Nihal C

    2012-01-01

    Emerging evidence points to monocarboxylates as key players in the pathophysiology of temporal lobe epilepsy (TLE) with hippocampal sclerosis (mesial temporal lobe epilepsy, MTLE). Monocarboxylate transporters (MCTs) 1 and 2, which are abundantly present on brain endothelial cells and perivascular...

  20. Urban Integrated Transportation Planning Based on Transit Oriented Development and its Research Challenges

    Institute of Scientific and Technical Information of China (English)

    Lu Huapu

    2005-01-01

    Satisfying the increasing traffic demand with the least amount of resource and environmental costs, the sustainable development object of urban traffic system determines that from long-term viewpoint, it is necessary to establish urban integrated traffic planning system with public transport as it is.The planning idea of Transit Oriented Development ( TOD ) is an important method to realize urban integrated traffic planning system. Research and practice reveal that harmony and integration is the key method to solve urban traffic problems. The integration of traffic system and land-use is the basic problem. Urban traffic development strategy with TOD provides ideas and ways to harmonize the traffic and land-use systems, which brings out a series of new research subjects and challenges in the field of traffic planning.

  1. Transport of ultracold neutrons through a mirror system with surface roughness as a velocity filter

    CERN Document Server

    Chizhova, L A; Jenke, T; Cronenberg, G; Geltenbort, P; Abele, H; Burgdörfer, J

    2012-01-01

    We perform classical Monte Carlo simulations of ultracold neutron transport through an absorbing-reflecting mirror system in the Earth's gravitational field. We show that the underlying mixed phase space of regular skipping motion and random motion due to disorder scattering can be exploited to realize a velocity filter for ultracold neutrons. The range of velocities selected is controlled by geometric parameters of the wave guide. Possible applications include investigations of transport and scattering dynamics in confined systems.

  2. A Two-Phase Cooling Loop for Fission Surface Power Waste Heat Transport Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Current lunar-based Fission Surface Power (FSP) Systems that will support sustained surface outposts consist of a nuclear reactor with power converters, whose waste...

  3. The use of modern information technology in research on transport accessibility

    Directory of Open Access Journals (Sweden)

    Bartosz BARTOSIEWICZ

    2015-09-01

    Full Text Available Transport accessibility can be analyzed using a number of different methods. The problem with each of them is the difficulty of obtaining data to measure this phenomenon The focus of this article and its main goal are to present methods and tools for gathering data on road traffic; thanks to modern information technology, it is possible to collect real data without the need for large-scale and highly capital-intensive measurements. The application of modern information technology (IT presented in the article, such as computer programs and applications like Google Maps Traffic Overlay and TomTom Live Traffic, enable research to be conducted on a scale that has thus far been unattainable, and allows information to be collected on such criteria as traffic volume, flow, average traffic speed, and actual journey time. Such innovative means of gathering data on automobile traffic open up new perspectives for assessing transport accessibility in terms of automobile traffic by providing high-quality data that meet the requirements for use in primary research.

  4. Effects of bulk charged impurities on the bulk and surface transport in three-dimensional topological insulators

    Science.gov (United States)

    Skinner, B.; Chen, T.; Shklovskii, B. I.

    2013-09-01

    In the three-dimensional topological insulator (TI), the physics of doped semiconductors exists literally side-by-side with the physics of ultrarelativistic Dirac fermions. This unusual pairing creates a novel playground for studying the interplay between disorder and electronic transport. In this mini-review, we focus on the disorder caused by the three-dimensionally distributed charged impurities that are ubiquitous in TIs, and we outline the effects it has on both the bulk and surface transport in TIs. We present self-consistent theories for Coulomb screening both in the bulk and at the surface, discuss the magnitude of the disorder potential in each case, and present results for the conductivity. In the bulk, where the band gap leads to thermally activated transport, we show how disorder leads to a smaller-than-expected activation energy that gives way to variable-range hopping at low temperatures. We confirm this enhanced conductivity with numerical simulations that also allow us to explore different degrees of impurity compensation. For the surface, where the TI has gapless Dirac modes, we present a theory of disorder and screening of deep impurities, and we calculate the corresponding zero-temperature conductivity. We also comment on the growth of the disorder potential in passing from the surface of the TI into the bulk. Finally, we discuss how the presence of a gap at the Dirac point, introduced by some source of time-reversal symmetry breaking, affects the disorder potential at the surface and the mid-gap density of states.

  5. A physically-based integrated numerical model for flow,upland erosion,and contaminant transport in surface-subsurface systems

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper presents a physically-based integrated hydrologic model that can simulate the rain-fall-induced 2D surface water flow, 3D variably saturated subsurface flow, upland soil erosion and transport, and contaminant transport in the surface-subsurface system of a watershed. The model couples surface and subsurface flows based on the assumption of continuity conditions of pressure head and exchange flux at the ground, considering infiltration and evapotranspiration. The upland rill/interrill soil erosion and transport are simulated using a non-equilibrium transport model. Contaminant transport in the integrated surface and subsurface domains is simulated using advection-diffusion equations with mass changes due to sediment sorption and desorption and exchanges between two domains due to infiltration, diffusion, and bed change. The model requires no special treatments at the interface of upland areas and streams and is suitable for wetland areas and agricultural watersheds with shallow streams.

  6. Transport signatures of surface potentials on three-dimensional topological insulators

    Science.gov (United States)

    Roy, Sthitadhi; Das, Sourin

    2016-02-01

    The spin-momentum-locked nature of the robust surface states of three-dimensional topological insulators (3D TIs) makes them promising candidates for spintronics applications. Surface potentials which respect time-reversal symmetry can exist at the surface between a 3D TI and the trivial vacuum. These potentials can distort the spin texture of the surface states while retaining their gapless nature. In this work, the effect of all such surface potentials on the spin textures is studied. Since a tunnel magnetoresistance signal carries the information of the spin texture, it is proposed that spin-polarized tunneling of electrons to a 3D TI surface can be used to uniquely identify the surface potentials and quantitatively characterize them.

  7. From Soil to Surface Water: a Meta-Analysis of Catchment-Scale Organic Matter Production and Transport

    Science.gov (United States)

    Gabor, R. S.; Brooks, P. D.; Perdrial, J. N.

    2015-12-01

    Organic matter plays a fundamental role in the ecology and biogeochemistry of many ecosystems, from soils to headwater streams to oceans. In most catchments, the terrestrial environment is the dominant source of organic matter for the aquatic system, and thus DOM represents a fundamental linkage between soil and surface water. With trends of increasing DOC concentrations observed in many areas of the world, there is growing interest in identifying which factors drive DOM concentration and chemistry. Studies of systems ranging from tropical rainforests to boreal landscapes have identified many catchment characteristics that co-vary with DOM concentration and chemistry. These include climate elements such as solar radiation and precipitation patterns, chemical measurements such as sulfate or chloride concentration, and land use impacts such as percent agriculture. The question of which catchment characteristics actually control DOM can be broken down into two parts: which factors control the production of mobile DOM and what drives DOM transport from the terrestrial to the aquatic system. Here we review studies covering a range of ecosystems, scales, and measurement techniques, to categorize the major state factors that drive catchment controls of aquatic organic matter. Specifically, we identify three major transport vectors that vary both in their timing of DOM transport to surface water and the propensity for DOM originating from terrestrial source areas to be modified during transport. We use this three vector conceptual model of transport to group catchments and identify reproducible signatures of DOM export with varying levels of disturbance. By developing a generalized conceptual model of catchment-scale controls on aquatic organic matter, we can predict how dissolved organic matter will respond to environmental change. This knowledge can then help guide best management practices.

  8. RESEARCH ON ADAPTIVE DATA COMPRESSION METHOD FOR TRIANGULATED SURFACES

    Institute of Scientific and Technical Information of China (English)

    Wang Wen; Wu Shixiong; Chen Zichen

    2004-01-01

    NC code or STL file can be generated directly from measuring data in a fast reverse-engineering mode.Compressing the massive data from laser scanner is the key of the new mode.An adaptive compression method based on triangulated-surfaces model is put forward.Normal-vector angles between triangles are computed to find prime vertices for removal.Ring data structure is adopted to save massive data effectively.It allows the efficient retrieval of all neighboring vertices and triangles of a given vertices.To avoid long and thin triangles,a new re-triangulation approach based on normalized minimum-vertex-distance is proposed,in which the vertex distance and interior angle of triangle are considered.Results indicate that the compression method has high efficiency and can get reliable precision.The method can be applied in fast reverse engineering to acquire an optimal subset of the original massive data.

  9. T tubules and surface membranes provide equally effective pathways of carbonic anhydrase-facilitated lactic acid transport in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Janine Hallerdei

    Full Text Available We have studied lactic acid transport in the fast mouse extensor digitorum longus muscles (EDL by intracellular and cell surface pH microelectrodes. The role of membrane-bound carbonic anhydrases (CA of EDL in lactic acid transport was investigated by measuring lactate flux in muscles from wildtype, CAIV-, CAIX- and CAXIV-single ko, CAIV-CAXIV double ko and CAIV-CAIX-CAXIV-triple ko mice. This was complemented by immunocytochemical studies of the subcellular localization of CAIV, CAIX and CAXIV in mouse EDL. We find that CAXIV and CAIX single ko EDL exhibit markedly but not maximally reduced lactate fluxes, whereas triple ko and double ko EDL show maximal or near-maximal inhibition of CA-dependent lactate flux. Interpretation of the flux measurements in the light of the immunocytochemical results leads to the following conclusions. CAXIV, which is homogeneously distributed across the surface membrane of EDL fibers, facilitates lactic acid transport across this membrane. CAIX, which is associated only with T tubular membranes, facilitates lactic acid transport across the T tubule membrane. The removal of lactic acid from the lumen of T tubuli towards the interstitial space involves a CO2-HCO3- diffusional shuttle that is maintained cooperatively by CAIX within the T tubule and, besides CAXIV, by the CAIV, which is strategically located at the opening of the T tubules. The data suggest that about half the CA-dependent muscular lactate flux occurs across the surface membrane, while the other half occurs across the membranes of the T tubuli.

  10. Spinel-structured surface layers for facile Li ion transport and improved chemical stability of lithium manganese oxide spinel

    Science.gov (United States)

    Lee, Hae Ri; Seo, Hyo Ree; Lee, Boeun; Cho, Byung Won; Lee, Kwan-Young; Oh, Si Hyoung

    2017-01-01

    Li-ion conducting spinel-structured oxide layer with a manganese oxidation state close to being tetravalent was prepared on aluminum-doped lithium manganese oxide spinel for improving the electrochemical performances at the elevated temperatures. This nanoscale surface layer provides a good ionic conduction path for lithium ion transport to the core and also serves as an excellent chemical barrier for protecting the high-capacity core material from manganese dissolution into the electrolyte. In this work, a simple wet process was employed to prepare thin LiAlMnO4 and LiMg0.5Mn1.5O4 layers on the surface of LiAl0.1Mn1.9O4. X-ray absorption studies revealed an oxidation state close to tetravalent manganese on the surface layer of coated materials. Materials with these surface coating layers exhibited excellent capacity retentions superior to the bare material, without undermining the lithium ion transport characteristics and the high rate performances.

  11. Impact of the Atmospheric Transport on the Seasonal Variations and Trends of the Surface Ozone Concentration at Caucasian and Central European Mountain Sites

    Science.gov (United States)

    Tarasova, O. A.; Staehelin, J.; Senik, I. A.; Sosonkin, M. G.; Cui, J.; Prevot, A. S.

    2008-12-01

    An analysis of the atmospheric transport influence on the seasonal variations and trends of the surface ozone for two mountain sites, namely Kislovodsk High Mountain Station (KHMS) in Caucasus, Russia (43.7°N, 42.7°E, 2070 m asl.) and Jungfraujoch (JFJ) in Switzerland (46.5°N, 7.9°E, 3580 m asl) will be presented. Transport patterns are analyzed using 3D LAGRANTO trajectories. Main transport directions are obtained with the help of k-means trajectories clustering for the period 1990-2006. For each selected cluster average seasonal cycle and trends at two mountain locations are analyzed. Due to non-monotonous behavior of the trend the entire period is divided into two subsets (1991-2001 and 1997- 2006) which are studied separately. For both sites (JFJ and KHMS) the highest spring maximum is observed in May in the cluster, originating in East Asia and traveling to both sites with the longest contact with the upper free troposphere. Moreover, for both locations the excess of the summer maximum above the spring one is observed in the cluster of the local/regional transport due to ozone photochemical production in the polluted continental PBL. Trend of the surface ozone concentration at JFJ in 1991-2001 is connected with increased ozone concentrations in the free troposphere of mid latitude over West Atlantic/USA influenced by stratospheric concentration increase (most positive spring trend in trans-Atlantic clusters). The response to the regional European emission decrease observed in the local/regional advection cluster is less important but it is contributing to the seasonality of the trend. In 1997-2006 the trends at JFJ are more connected with European emissions regulations (the strongest trend are in the cluster of local/regional advection). The strong negative trends of the surface ozone concentrations at KHMS during both considered periods (1991-2001 and 1996-2007) are likely to be associated with different regime of emission (both of the local and regional

  12. Transport properties of iron-porphyrin molecule sandwiched between Au surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Hisashi [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: KONDO.Hisashi@nims.go.jp; Kino, Hiori; Nara, Jun [CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Ohno, Takahisa [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); MANA, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2008-09-30

    The transport properties of an iron-porphyrin molecule sandwiched between Au(1 1 1) electrodes are investigated using the non-equilibrium Green's function method based on the density functional theory, and in particular, the dependence on a terminal-atom position is studied. We consider four models for terminal-atom positions. It is found that the transport properties of the junction system are very sensitive to a terminal-atom position. We also find that the contribution of the d-orbitals of the Fe atom to the transport properties around the Fermi energy strongly changes, depending on a terminal-atom position. From these results, we propose a suitable terminal-atom position for the molecular sensor discussed in the other paper.

  13. Pseudospin-valve effect on transport in junctions of three-dimensional topological insulator surfaces

    Science.gov (United States)

    Roy, Sthitadhi; Roychowdhury, Krishanu; Das, Sourin

    2016-07-01

    We show that the surface states of pristine 3D topological insulators (TIs) are analogs of ferromagnetic half metals due to complete polarization of an emergent momentum independent pseudospin (SU(2)) degree of freedom on the surface. To put this claim on firm footing, we present results for TI surfaces perpendicular to the crystal growth axis, which clearly show that the tunneling conductance between two such TI surfaces of the same TI material is dominated by this half metallic behavior leading to physics reminiscent of a spin-valve. Further using the generalized tunnel magnetoresistance derived in this work we also study the tunneling current between arbitrary TI surfaces. We also perform a comprehensive study of the effect of all possible surface potentials allowed by time reversal symmetry on this spin-valve effect and show that it is robust against most of such potentials.

  14. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B

    Institute of Scientific and Technical Information of China (English)

    MENG Yan; ZHAO ChunYan; ZHANG XueXin; ZHAO HuaShan; GUO LiRong; Lü Bin; ZHAO XueJian; YANG BaoXue

    2009-01-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead Ⅱ) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by float-ing microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5±4.2), (45.5±6.9) and (43.8±7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6±2.9), (38.7±5.6) and (38.2±7.3) ms, P<0.05). The atrial ventricular heart block type Ⅱ and Ⅲ only appeared in the aging UT-B null mice (52 w old). The amplitude of action potential and Vmax decreased significantly in UT-B null mice ((92.17±10.56) and (101.89±9.54) mV/s) vs those in wild-type mice (vs (110.51±10.38) and (109.53±10.64) mV/s, P<0.05). The action potential duration at 50% and 90% (APD50 and APD90) was significantly prolonged in UT-B null mice ((123.83±11.17) and (195.43±16.41) ms) vs that in wild-type mice ((108.27±10.85) and (171.00±15.53) ms, P<0.05). The maximal sodium current decreased significantly in UT-B null mice (-8.80±0.92) nA vs that in wild-type mice ((-5.98±1.07) nA, P<0.05). These results provide the first evidence that UT-B deletion causes progressive heart block in mice.

  15. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead II) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by floating microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5 ± 4.2), (45.5 ± 6.9) and (43.8 ± 7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6 ± 2.9), (38.7 ± 5.6) and (38.2 ± 7.3) ms, P<0.05). The atrial ventricular heart block type II and III only appeared in the aging UT-B null mice (52 w old). The amplitude of action potential and Vmax decreased significantly in UT-B null mice ((92.17 ± 10.56) and (101.89 ± 9.54) mV/s) vs those in wild-type mice (vs (110.51 ± 10.38) and (109.53 ± 10.64) mV/s, P<0.05). The action potential duration at 50% and 90% (APD50 and APD90) was significantly prolonged in UT-B null mice ((123.83 ± 11.17) and (195.43 ± 16.41) ms) vs that in wild-type mice ((108.27 ± 10.85) and (171.00 ± 15.53) ms, P<0.05). The maximal sodium current decreased significantly in UT-B null mice (-8.80 ± 0.92) nA vs that in wild-type mice ((-5.98 ± 1.07) nA, P<0.05). These results provide the first evidence that UT-B deletion causes progressive heart block in mice.

  16. 76 FR 27745 - Wireless Innovation for Transportation; Request for Information

    Science.gov (United States)

    2011-05-12

    ... Research and Innovative Technology Administration Wireless Innovation for Transportation; Request for... surface transportation. The President's Wireless Infrastructure and Innovation Initiative includes a.... Additional information about the USDOT's planned work under the Wireless Innovation and...

  17. Distributions of clay minerals in surface sediments of the middle Bay of Bengal: Source and transport pattern

    Science.gov (United States)

    Li, Jingrui; Liu, Shengfa; Shi, Xuefa; Feng, Xiuli; Fang, Xisheng; Cao, Peng; Sun, Xingquan; Wenxing, Ye; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

    2017-08-01

    The clay mineral contents in 110 surface sediment samples collected from the middle of the Bay of Bengal were analyzed by X-ray diffraction (XRD) to investigate the provenance and transport patterns. The illite content was highest, followed by chlorite, kaolinite and then smectite, with average weight percent distributions of 52%, 22%, 14% and 12%, respectively. Illite and chlorite had similar distribution pattern, with higher contents in the northern and central areas and lower contents in the southern area, whereas smectite showed the opposite distribution pattern. Kaolinite show no obvious higher or lower areas and the southern ;belt; was one of the highest content areas. Based on the spatial distribution characteristics and cluster analysis results, the study area can be classified into two provinces. Province I covers the southwestern area and contains high concentrations of illite and smectite sediments. Province II covers most sites and is also characterized by high concentrations of illite, but the weight percent of smectite is only half of that of province I. According to a quantitative estimate using end-member clay minerals contents, the relative contributions from the Himalayan source and the Indian source are 63% and 37% on average, respectively. Integrative analysis indicates that the hydrodynamic environment in the study area, especially the turbidity and surface monsoonal circulation, plays an important role in the spatial distribution and dispersal of the clay fraction in the sediments. The sediments in province I are mainly from the Indian source transported by the East Indian Coastal Current (EICC) and the surface monsoon circulation with minor contributions from the Himalayan source while the sediments in province II are mainly from the Himalayan source transported by turbidity and surface monsoonal circulation with little contribution from Indian river materials.

  18. Decadal Arctic surface atmosphere/ocean heat budgets and mass transport estimates from several atmospheric and oceanic reanalyses

    Science.gov (United States)

    Chepurin, gennaday; Carton, James

    2017-04-01

    The Arctic is undergoing dramatic changes associated with the loss of seasonal and permanent ice pack. By exposing the surface ocean to the atmosphere these changes dramatically increase surface exchange processes. In contrast, increases in freshwater and heat input decreases turbulent exchanges within the ocean. In this study we present results from an examination of changing ocean heat flux, storage, and transport during the 36 year period 1980-2015. To identify changes in the surface atmosphere we examine three atmospheric reanalyses: MERRA2, ERA-I, and JRA55. Significant differences in fluxes from these reanalyses arise due to the representation of clouds and water vapor. These differences provide an indication of the uncertainties in the historical record. Next we turn to the Simple Ocean Data Assimilation version 3 (SODA3) global ocean/sea ice reanalysis system to allow us to infer the full ocean circulation from the limited set of historical record of ocean observations. SODA3 has 10 km horizontal resolution in the Arctic and assimilates the full suite of historical marine temperature and salinity observations. To account for the uncertainties in atmospheric forcing, we repeat our analysis with each of the three atmospheric reanalyses. In the first part of the talk we review the climatological seasonal surface fluxes resulting from our reanalysis system, modified for consistency with the ocean observations, and the limits of what we can learn from the historical record. Next we compare the seasonal hydrography, heat, and mass transports with direct estimates from moorings. Finally we examine the impact on the Arctic climate of the changes in sea ice cover and variability and trends of ocean/sea ice heat storage and transport and their contributions to changes in the seasonal stratification of the Arctic Ocean.

  19. Lagrangian study of surface transport in the Kuroshio Extension area based on simulation of propagation of Fukushima-derived radionuclides

    CERN Document Server

    Prants, S V; Uleysky, M Yu

    2013-01-01

    Lagrangian approach is applied to study near-surface large-scale transport in the Kuroshio Extension area using a simulation with synthetic particles advected by AVISO altimetric velocity field. A material line technique is applied to find the origin of water masses in cold-core cyclonic rings pinched off from the jet in summer 2011. Tracking and Lagrangian maps provide the evidence of cross-jet transport. Fukushima derived caesium isotopes are used as Lagrangian tracers to study transport and mixing in the area a few months after the March of 2011 tsunami that caused a heavy damage of the Fukushima nuclear power plant (FNPP). Tracking maps are computed to trace the origin of water parcels with measured levels of Cs-134 and Cs-137 concentrations collected in two R/V cruises in June and July 2011 in the large area of the Northwest Pacific. It is shown that Lagrangian simulation is useful to finding the surface areas that are potentially dangerous due to the risk of radioactive contamination. The results of sim...

  20. Transport Properties and Surface Morphology Correlated Studies on Graphene Formed by Si Desorption of 6H-SiC

    Science.gov (United States)

    Roach, William; Beringer, Douglas; Skuza, Jonathan; Clavero, Cesar; Lukaszew, Rosa Alejandra

    2009-11-01

    Interest in graphene, a single layer of carbon atoms arranged in a hexagonal lattice, has increased in recent years due to exciting characteristics such as its predicted high mobility [1]. However, developing a method to produce graphene that is easily integrated into existing fabrication processes has proved difficult thus far. One promising method is high temperature annealing of 6H-SiC such that Si desorption occurs [2], although this method leads to graphene that exhibits lower mobility than predicted [3]. Thus, we have investigated the relationship between different growth conditions (i.e. annealing time and temperature), the resulting surface morphology and the transport properties of graphene films produced using this method. Raman spectroscopy, atomic force microscopy, and Van der Pauw Hall mobility measurements have been used to correlate the surface morphology to transport properties of graphene formed on SiC. Understanding the effect of growth conditions on the resulting transport properties will help optimize the fabrication of graphene for use in the next generation of electronic devices and other applications. [1] Novoselov et al., Science 306, 666 (2004). [2] C. Berger et al., J. Phys. Chem. B 108, 19912 (2004). [3] G. Gu et al., Appl. Phys. Lett. 90, 253507 (2007).

  1. Transonic unsteady airloads on an energy efficient transport wing with oscillating control surfaces

    Science.gov (United States)

    Sandford, M. C.; Ricketts, R. H.; Cazier, F. W., Jr.; Cunningham, H. J.

    1980-01-01

    An aspect ratio 10.8 supercritical wing with oscillating control surfaces is described. The wing is instrumental with 252 static orifices and 164 in situ dynamic pressure transducers for studying the effects of control surface deflection on steady and unsteady pressures at transonic speeds. Results from initial wind tunnel tests conducted in the Langley Transonic Dynamics Tunnel are discussed. Unsteady pressure results are presented for two trailing edge control surfaces oscillating separately at the design Mach number of 0.78. Some experimental results are compared with analytical results obtained by using linear lifting surface theory.

  2. Molecular dynamics study on mechanism of preformed particle gel transporting through nanopores: Surface chemistry and heterogeneity

    Science.gov (United States)

    Cui, Peng; Zhang, Heng; Ma, Ying; Hao, Qingquan; Liu, Gang; Sun, Jichao; Yuan, Shiling

    2017-10-01

    The translocation behavior of preformed particle gel (PPG) in porous media is crucial for its application in enhanced oil recovery. By means of non-equilibrium molecular dynamics simulation, the translocation mechanism of PPG confined in different silica nanopores were investigated. The influence of surface chemistry and chemical heterogeneity of silica nanopore on the translocation process was revealed. As the degree of surface hydroxylation increases and the heterogeneity decreases, the pulling force needed to drive PPG decreases. We infer that the nanopore's surface (i.e. surface chemistry and heterogeneity) affects the translocation of PPG indirectly by forming different hydration layers.

  3. Atmospheric transport and deposition of mineral dust to the ocean: implications for research needs.

    Science.gov (United States)

    Schulz, Michael; Prospero, Joseph M; Baker, Alex R; Dentener, Frank; Ickes, Luisa; Liss, Peter S; Mahowald, Natalie M; Nickovic, Slobodan; García-Pando, Carlos Pérez; Rodríguez, Sergio; Sarin, Manmohan; Tegen, Ina; Duce, Robert A

    2012-10-01

    This paper reviews our knowledge of the measurement and modeling of mineral dust emissions to the atmosphere, its transport and deposition to the ocean, the release of iron from the dust into seawater, and the possible impact of that nutrient on marine biogeochemistry and climate. Of particular concern is our poor understanding of the mechanisms and quantities of dust deposition as well as the extent of iron solubilization from the dust once it enters the ocean. Model estimates of dust deposition in remote oceanic regions vary by more than a factor of 10. The fraction of the iron in dust that is available for use by marine phytoplankton is still highly uncertain. There is an urgent need for a long-term marine atmospheric surface measurement network, spread across all oceans. Because the southern ocean is characterized by large areas with high nitrate but low chlorophyll surface concentrations, that region is particularly sensitive to the input of dust and iron. Data from this region would be valuable, particularly at sites downwind from known dust source areas in South America, Australia, and South Africa. Coordinated field experiments involving both atmospheric and marine measurements are recommended to address the complex and interlinked processes and role of dust/Fe fertilization on marine biogeochemistry and climate.

  4. Climatology of wintertime long-distance transport of surface-layer air masses arriving urban Beijing in 2001-2012

    Science.gov (United States)

    Chen, Bin; Xiang-De, XU

    2017-02-01

    In this study, the FLEXPART-WRF coupled modeling system is used to conduct 12-year Lagrangian modeling over Beijing, China, for the winters of 2001-2012. Based on large trajectory tracking ensembles, the long-range air transport properties, in terms of geographic source regions within the atmospheric planetary boundary layer (PBL) and large-scale ventilation, and its association with air quality levels were quantified from a climatological perspective. The results show the following: (1) The air masses residing in the near-surface layer over Beijing potentially originate from broader atmospheric boundary-layer regions, which cover vast areas with the backward tracking time elapsed. However, atmospheric transport from northeastern China and, to a lesser extent, from the surrounding regions of Beijing is important. (2) The evolution of air quality over Beijing is negatively correlated with large-scale ventilation conditions, particularly at a synoptic timescale. Thus, the simple but robust backward-trajectory ventilation (BV) index defined in this study could facilitate operational forecasting of severe air pollution events. (3) By comparison, the relatively short-range transport occurring over transport timescales of less than 3 days from southern and southeastern Beijing and its surrounding areas plays a vital role in the formation of severe air pollution events during the wintertime. (4) Additionally, an interannual trend analysis suggests that the geographic sources and ventilation conditions also changed, at least over the last decade, corresponding to the strength variability of the winter East Asian monsoon.

  5. Stability and transport of graphene oxide nanoparticles in groundwater and surface water

    Science.gov (United States)

    A transport study investigating the effects of natural organic matter (NOM) in the presence of monovalent (KCl) and divalent (CaCl2) salts was performed in a packed bed column. The electrophoretic mobility (EPM) and effective diameter of the graphene oxide nanoparticles (GONPs) were measured as a fu...

  6. Solute Transport of Negatively Charged Contrast Agents Across Articular Surface of Injured Cartilage.

    Science.gov (United States)

    Kokkonen, H T; Chin, H C; Töyräs, J; Jurvelin, J S; Quinn, T M

    2017-04-01

    Solute transport through the extracellular matrix (ECM) is crucial to chondrocyte metabolism. Cartilage injury affects solute transport in cartilage due to alterations in ECM structure and solute-matrix interactions. Therefore, cartilage injury may be detected by using contrast agent-based clinical imaging. In the present study, effects of mechanical injury on transport of negatively charged contrast agents in cartilage were characterized. Using cartilage plugs injured by mechanical compression protocol, effective partition coefficients and diffusion fluxes of iodine- and gadolinium-based contrast agents were measured using high resolution microCT imaging. For all contrast agents studied, effective diffusion fluxes increased significantly, particularly at early times during the diffusion process (38 and 33% increase after 4 min, P integrity in cartilage superficial zone. This study suggests that alterations in contrast agent diffusion flux, a non-equilibrium transport parameter, provides a more sensitive indicator for assessment of cartilage matrix integrity than partition coefficient and the equilibrium distribution of solute. These findings may help in developing clinical methods of contrast agent-based imaging to detect cartilage injury.

  7. 77 FR 10599 - Surface Transportation Project Delivery Pilot Program; Caltrans Audit Report

    Science.gov (United States)

    2012-02-22

    ...) Interviews with staff indicated a large staff turnover in certain Districts. The loss of experienced staff... agency staff at the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service (FWS), the National... Transportation Systems Center; U.S. FWS. During the onsite audit, the audit team interviewed more than 60 staff...

  8. Research on impervious surface dynamic changes based on Landsat satellite images in Nantong, China

    Science.gov (United States)

    Lu, Xiu; Li, Jia; Duan, Ping; Wang, Jinliang; Zhang, Chi

    2016-10-01

    In this paper, the decision tree classification based on the CART algorithm (Classification and Regression Tree) is used to extract the impervious surface area of Nantong city in Jiangsu Province in China. Impervious surface dynamic change nearly 25 years in Nantong city is researched using four periods Landsat images of 1990, 2003, 2008, and 2014. The results show that the classification precision based on the CART algorithm is higher, which can more accurately extract the impervious surface. During the 25 years, the trend of the impervious surface of Nantong is increased year by year. Urban construction and expansion is one of the driving forces of the impervious surface increase.

  9. Research on Some Bus Transport Networks with Random Overlapping Clique Structure

    Institute of Scientific and Technical Information of China (English)

    YANG Xu-Hua; WANG Bo; WANG Wan-Liang; SUN You-Xian

    2008-01-01

    On the basis of investigating the statistical data of bus transport networks of three big cities in China, we propose that each bus route is a clique (maximal complete subgraph) and a bus transport network (BTN) consists of a lot of cliques, which intensively connect and overlap with each other. We study the network properties, which include the degree distribution, multiple edges' overlapping time distribution, distribution of the overlap size between any two overlapping cliques, distribution of the number of cliques that a node belongs to. Naturally, the cliques also constitute a network, with the overlapping nodes being their multiple links. We' also research its network properties such as degree distribution, clustering, average path length, and so on. We propose that a BTN has the properties of random clique increment and random overlapping clique, at the same time, a BTN is a small-world network with highly clique-clustered and highly clique-overlapped. Finally, we introduce a BTN evolution model, whose simulation results agree well with the statistical laws that emerge in real BTNs.

  10. Overview of research and development in subsurface fate and transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, T.M. [Brookhaven National Lab., Upton, NY (United States); Chehata, M. [Science Applications Internationa Corp. (United States)

    1995-05-01

    The US Department of Energy is responsible for the remediation of over 450 different subsurface-contaminated sites. Contaminant plumes at these sites range in volume from several to millions of cubic yards. The concentration of contaminants also ranges over several orders of magnitude. Contaminants include hazardous wastes such as heavy metals and organic chemicals, radioactive waste including tritium, uranium, and thorium, and mixed waste, which is a combination of hazardous and radioactive wastes. The physical form of the contaminants includes solutes, nonaqueous phase liquids (NAPLs), and vapor phase contaminants such as volatilized organic chemicals and radon. The subject of contaminant fate and transport modeling is multi-disciplinary, involving hydrology, geology, microbiology, chemistry, applied mathematics, computer science, and other areas of expertise. It is an issue of great significance in the United States and around the world. As such, many organizations have substantial programs in this area. In gathering data to prepare this report, a survey was performed of research and development work that is funded by US government agencies to improve the understanding and mechanistic modeling of processes that control contaminant movement through subsurface systems. Government agencies which fund programs that contain fate and transport modeling components include the Environmental Protection Agency, Nuclear Regulatory Commission, Department of Agriculture, Department of Energy, National Science Foundation, Department of Defense, United States Geological Survey, and National Institutes of Health.

  11. Overview of research and development in subsurface fate and transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, T.M. [Brookhaven National Lab., Upton, NY (United States); Chehata, M. [Science Applications Internationa Corp. (United States)

    1995-05-01

    The US Department of Energy is responsible for the remediation of over 450 different subsurface-contaminated sites. Contaminant plumes at these sites range in volume from several to millions of cubic yards. The concentration of contaminants also ranges over several orders of magnitude. Contaminants include hazardous wastes such as heavy metals and organic chemicals, radioactive waste including tritium, uranium, and thorium, and mixed waste, which is a combination of hazardous and radioactive wastes. The physical form of the contaminants includes solutes, nonaqueous phase liquids (NAPLs), and vapor phase contaminants such as volatilized organic chemicals and radon. The subject of contaminant fate and transport modeling is multi-disciplinary, involving hydrology, geology, microbiology, chemistry, applied mathematics, computer science, and other areas of expertise. It is an issue of great significance in the United States and around the world. As such, many organizations have substantial programs in this area. In gathering data to prepare this report, a survey was performed of research and development work that is funded by US government agencies to improve the understanding and mechanistic modeling of processes that control contaminant movement through subsurface systems. Government agencies which fund programs that contain fate and transport modeling components include the Environmental Protection Agency, Nuclear Regulatory Commission, Department of Agriculture, Department of Energy, National Science Foundation, Department of Defense, United States Geological Survey, and National Institutes of Health.

  12. Single-electron transport driven by surface acoustic waves: Moving quantum dots versus short barriers

    DEFF Research Database (Denmark)

    Utko, Pawel; Hansen, Jørn Bindslev; Lindelof, Poul Erik;

    2007-01-01

    We have investigated the response of the acoustoelectric-current driven by a surface-acoustic wave through a quantum point contact in the closed-channel regime. Under proper conditions, the current develops plateaus at integer multiples of ef when the frequency f of the surface-acoustic wave or t...

  13. One decade of research into the fate and transport of carbon-based nanomaterials - Lessons learnt and future perspectives

    Science.gov (United States)

    Hüffer, Thorsten; Hofmann, Thilo

    2016-04-01

    Carbon-based nanomaterials (CNM) exhibit unique physico-chemical properties (e.g., large surface area to volume ratios, electron delocalization), which make them promising for a great number of applications. The production, use, and disposal of CNM and CNM-containing products will inevitably result in the release of these materials into the environment. The fate and transport of CNM greatly depends on their physico-chemical properties and surrounding environmental conditions. This field of research has constantly increased over recent years. Yet little is known on how transformation processes such as changes in surface properties or aggregation influence their interaction with other environmental species (i.e., solid surfaces or contaminants). For example, changes in redox chemistry in combination with irradiation have shown to significantly alter the surface chemistry of C60 fullerenes and consequently decreased their sorption affinity towards non-polar organic contaminants [1]. The presence of natural organic matter (NOM) seems to play a major role on the aggregation of CNM; however, the results are not consistent whether this leads to an increase or decrease in interactions with solid surfaces or contaminants. Either increased interactions resulting from a higher dispersion of CNM or decreased interactions of CNM, which was assigned to an offset of "creating" new sorption sites due to increased dispersion by a reduced accessibility of polar moieties. For the latter effect, NOM was proposed to either directly compete for sorption sites on CNM surface or a blocking of CNM pores by large NOM molecules [2]. The potential consequences of these changes in surface properties of CNM on their toxic effects on microorganisms have only been partially examined. For an environmental risk assessment, data on the occurrence of CNM is obligatory but to date the environmental concentrations of CNM are still difficult to assess due to still unsolved analytical issues in matrix

  14. Requirements for a systems-based research and development management process in transport infrastructure engineering

    Directory of Open Access Journals (Sweden)

    Rust, Frederik Christoffel

    2015-05-01

    Full Text Available The management of research and development (R&D in the transport infrastructure field is complex due to the multidisciplinary nature of the work. The literature shows that linear R&D models that progress from idea through to consumer product are not suitable for the management of such multi-disciplinary projects. This study focuses on determining the key characteristics required for a systems-based approach to the management of R&D projects. The information and data was compiled from literature reviews, interviews, and an e-mail survey with responses from 42 significant international R&D programmes. The findings confirmed the need for a systems-based approach to R&D management. The study formulated twelve principles or tenets for a new, systems-based approach.

  15. Applications of endothermic research technology to the high speed civil transport

    Science.gov (United States)

    Glickstein, M. R.; Spadaccini, L. J.

    1997-01-01

    The success of strategies for controlling emissions and enhancing performance in High Speed Research applications may be increased by more effective utilization of the heat sink afforded by the fuel in the vehicle thermal management system. This study quantifies the potential benefits associated with the use of supercritical preheating and endothermic cracking of jet fuel prior to combustion to enhance the thermal management capabilities of the propulsion systems in the High Speed Civil Transport (HSCT). A fuel-cooled thermal management system, consisting of plate-fin heat exchangers and a small auxiliary compressor, is defined for the HSCT, integrated with the engine, and an assessment of the effect on engine performance, weight, and operating cost is performed. The analysis indicates significant savings due a projected improvement in fuel economy, and the potential for additional benefit if the cycle is modified to take full advantage of all the heat sink available in the fuel.

  16. Research on the Behavior Characteristics of Pedestrian Crowd Weaving Flow in Transport Terminal

    Directory of Open Access Journals (Sweden)

    Liya Yao

    2012-01-01

    Full Text Available Due to the poor transfer organization in urban public transport terminal, pedestrian crowd are often forced to weaving in their transfer flow lines. Frequent weaving behaviors not only decrease passengers’ transfer comfort, but may also trigger serious crowd disaster such as trampling. In order to get accurate understanding of the weaving features of pedestrian crowd and analyze the relevant evolution law, researches have been conducted on the basis of field investigation. First, the typical weaving phenomenon were defined and classified, and a microscopic parameters system of pedestrian crowd weaving flow was constructed. The detection and quantification methods of multiple indicator parameters were also given. Then, correlation between different behavioral parameters was analyzed based on the survey data of weaving pedestrian crowd on the stairs of DongZhiMen (DZM hub. The basic characteristics and evolution law of the weaving behaviors were then discussed, and conclusions were drawn.

  17. Flexible Surface Hopping Approach to Model the Crossover from Hopping to Band-like Transport in Organic Crystals.

    Science.gov (United States)

    Wang, Linjun; Beljonne, David

    2013-06-06

    Two distinct pictures are usually evoked when modeling charge transport in organic crystals, that is, band and hopping models, the signature of which is conveyed by a characteristic temperature dependence of mobility. Here, we present a novel flexible surface hopping approach compliant with general Hamiltonians that is able to grasp the crossover from hopping to band-like transport regimes. This approach is applied to solve a one-dimensional mixed quantum-classical model and to calculate the temperature dependence of charge mobility along with the degree of charge spatial localization. It is found that the roles of both local and nonlocal electron-phonon couplings strongly depend on the intrinsic charge localization strength.

  18. Effect of Surface-optical Phonons on the Charge Transport in Wrap-gated Semiconducting Nanowire Field-effect Transistors

    Science.gov (United States)

    Konar, Aniruddha; Fang, Tian; Jena, Debdeep

    2010-03-01

    Surface phonons (SO-phonons) arise at the boundary of two different dielectric mediums. Though the effect of electron-surface phonon scattering on low-filed charge transport has been studied extensively for thin Si-MOSFET [1] and graphene [2], its effect on the 1D nanowire devices has not studied so far. Vibrating diploes in polar gate-dielectric induces a time-varying potential inside the nanowires. The frequencies of these time-varying fields have been calculated by implementing electrostatic boundary conditions at different interfaces of nanowire-dielectric-metal system. Our calculation shows that the electron-SO phonon interaction strength decays exponentially from the gate-nanowire interface towards the nanowire axis. Electron-SO phonon scattering rate has been calculated using Boltzmann transport equation under relaxation time approximation. We find that for thin nanowires (radius 1-20 nm), electron-SO phonon scattering rate is comparable to other dominant scattering mechanisms (such as impurity and bulk optical phonon scatterings) and reduces carrier mobility significantly. Calculating surface-phonon limited mobility of Si nanowires on various available common dielectrics, we have predicted the optimum choice of gate-dielectrics for nanowire-based electronic devices. [4pt] [1] M. V. Fischetti et. al J. Appl. Phys. 90 4581 (2001). [0pt] [2] A. Konar et. al. arXiv: 0902.0819.

  19. Evaluation of the surface structure of composite restorations in light of own pilot research

    OpenAIRE

    Chalas Renata; Orlowski Miroslaw; Tarczydlo Bozena; Zubrzycka-Wrobel Joanna; Maj Karol; Wojcik-Checinska Ilona

    2016-01-01

    Research on the dental restorative materials employed in remedying dental cavities has been conducted on many levels and areas, both with application of clinical and laboratory methods. One of the elements that determines whether the restoration may be degraded is the condition of its surface. The aim of the study was to assess the texture surface of composite restorations using a non-contact method of teeth models scanning. In this work, ten medium size cavities on the occlusal surfaces of m...

  20. Numerical research on the anisotropic transport of thermal neutron in heterogeneous porous media with micron X-ray computed tomography

    OpenAIRE

    Yong Wang; Wenzheng Yue; Mo Zhang

    2016-01-01

    The anisotropic transport of thermal neutron in heterogeneous porous media is of great research interests in many fields. In this paper, it is the first time that a new model based on micron X-ray computed tomography (CT) has been proposed to simultaneously consider both the separation of matrix and pore and the distribution of mineral components. We apply the Monte Carlo method to simulate thermal neutrons transporting through the model along different directions, and meanwhile detect those ...

  1. Turbulent momentum transport due to the beating between different tokamak flux surface shaping effects

    CERN Document Server

    Ball, Justin

    2016-01-01

    Introducing up-down asymmetry into the tokamak magnetic equilibria appears to be a feasible method to drive fast intrinsic toroidal rotation in future large devices. In this paper we investigate how the intrinsic momentum transport generated by up-down asymmetric shaping scales with the mode number of the shaping effects. Making use the gyrokinetic tilting symmetry (Ball et al (2016) Plasma Phys. Control. Fusion 58 045023), we study the effect of envelopes created by the beating of different high-order shaping effects. This reveals that the presence of an envelope can change the scaling of the momentum flux from exponentially small in the limit of large shaping mode number to just polynomially small. This enhancement of the momentum transport requires the envelope to be both up-down asymmetric and have a spatial scale on the order of the minor radius.

  2. Plasmonic Hot Electron Transport Driven Site-Specific Surface-Chemistry with Nanoscale Spatial Resolution

    CERN Document Server

    Cortés, Emiliano; Cambiasso, Javier; Jermyn, Adam S; Sundararaman, Ravishankar; Narang, Prineha; Schlücker, Sebastian; Maier, Stefan A

    2016-01-01

    Nanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive. Here we spatially map hot-electron-driven reduction chemistry with 15 nanometre resolution as a function of time and electromagnetic field polarization for different plasmonic nanostructures. We combine experiments employing a six-electron photo-recycling process that modify the terminal group of a self-assembled monolayer on plasmonic silver nanoantennas, with theoretical predictions from first-principles calculations of non-equilibrium hot-carrier transport in these systems. The resulting localization of reactive regions, determined by hot carrier transport from...

  3. Turbulent momentum transport due to the beating between different tokamak flux surface shaping effects

    Science.gov (United States)

    Ball, Justin; Parra, Felix I.

    2017-02-01

    Introducing up-down asymmetry into the tokamak magnetic equilibria appears to be a feasible method to drive fast intrinsic toroidal rotation in future large devices. In this paper we investigate how the intrinsic momentum transport generated by up-down asymmetric shaping scales with the mode number of the shaping effects. Making use the gyrokinetic tilting symmetry (Ball et al 2016 Plasma Phys. Control. Fusion 58 045023), we study the effect of envelopes created by the beating of different high-order shaping effects. This reveals that the presence of an envelope can change the scaling of the momentum flux from exponentially small in the limit of large shaping mode number to just polynomially small. This enhancement of the momentum transport requires the envelope to be both up-down asymmetric and have a spatial scale on the order of the minor radius.

  4. Can clouds enhance long-range transport of low volatile, ionizable and surface-active chemicals?

    DEFF Research Database (Denmark)

    Franco, Antonio; Trapp, Stefan

    2011-01-01

    Atmospheric partitioning and transport of low volatile organic compounds is strongly influenced by the presence of water (e.g. clouds) and its deposition velocity (e.g. rainfall, snow). It was identified that the assumption of continuous rainfall underestimates the residence time and the transport...... substances. A modified version of the regional multimedia activity model for ionics MAMI, including twolayered atmosphere with atmospheric boundary layer (ABL) and lower/middle troposphere (LMT), interface partitioning, intermittent rainfall and variable cloud coverage was applied to a selection of ten low...... were run for a constant emission to the atmospheric boundary layer to identify key model inputs. The degradation rate, the duration of dry and wet periods and the parameters describing air-water bulk partitioning (KAW and T) and ionization (pKa and pH) determine the residence time in the ABL...

  5. The Research on Friction Characteristics of Non Smooth Bionic Mesoscopic Surface

    Directory of Open Access Journals (Sweden)

    Su Chunjian

    2014-12-01

    Full Text Available The application of using friction to transmit power and prevent slippage is very widely used, many animals have very strong adhesion climbing ability, and it has important theoretical significance and wide application prospect to research and the prepare bionic surface to increase transmission friction using the bionic technology. In recent years, the research of foot structure of climbing animals shows that their surface morphology has both macro and micro scale features, and only study from the macro to the micro scale surface structure can be better elucidate the mechanism of increasing-friction of climbing animal. This paper will study bionic surface structure on mesoscopic scale from micron to millimeter level, research the influence of foot structure of climbing animal under mesoscopic scale on characteristics of increasing friction using bionic technology, prepare the bionic non-smooth surface of convex or concave using bionic manufacturing technology, establish the friction model of non-smooth surface, investigate the increasing-friction mechanism of the bionic surface morphology on mesoscopic scales, reveals the influence of surface morphology, layout, size and material properties on the friction characteristics, provide the design of bionic friction surface and calculation method of friction coefficient and provide reliable theoretical basis for engineering application.

  6. GPS based surface displacements – a proxy for discharge and sediment transport from the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Hasholt, Bent; Khan, Shfaqat Abbas; Mikkelsen, Andreas Bech

    2014-01-01

    The elastic respond of the Earth’s surface to mass changes has been measured with Global Positioning System (GPS). Mass loss as accumulated runoff and sediment transport from a 10000 km2 segment of the Greenland Ice Sheet (GrIS) correlated very well (R2=0.83) with GPS measured uplift. Accumulated....... Based on the entire GPS record (1996–2013), it is shown that until 2005–2006 the mass balance of this segment of the GrIS was rather stable – since then there has been an increasing loss of mass, culminating in 2012....

  7. Updated model for radionuclide transport in the near-surface till at Forsmark - Implementation of decay chains and sensitivity analyses

    Energy Technology Data Exchange (ETDEWEB)

    Pique, Angels; Pekala, Marek; Molinero, Jorge; Duro, Lara; Trinchero, Paolo; Vries, Luis Manuel de [Amphos 21 Consulting S.L., Barcelona (Spain)

    2013-02-15

    The Forsmark area has been proposed for potential siting of a deep underground (geological) repository for radioactive waste in Sweden. Safety assessment of the repository requires radionuclide transport from the disposal depth to recipients at the surface to be studied quantitatively. The near-surface quaternary deposits at Forsmark are considered a pathway for potential discharge of radioactivity from the underground facility to the biosphere, thus radionuclide transport in this system has been extensively investigated over the last years. The most recent work of Pique and co-workers (reported in SKB report R-10-30) demonstrated that in case of release of radioactivity the near-surface sedimentary system at Forsmark would act as an important geochemical barrier, retarding the transport of reactive radionuclides through a combination of retention processes. In this report the conceptual model of radionuclide transport in the quaternary till at Forsmark has been updated, by considering recent revisions regarding the near-surface lithology. In addition, the impact of important conceptual assumptions made in the model has been evaluated through a series of deterministic and probabilistic (Monte Carlo) sensitivity calculations. The sensitivity study focused on the following effects: 1. Radioactive decay of {sup 135}Cs, {sup 59}Ni, {sup 230}Th and {sup 226}Ra and effects on their transport. 2. Variability in key geochemical parameters, such as the composition of the deep groundwater, availability of sorbing materials in the till, and mineral equilibria. 3. Variability in hydraulic parameters, such as the definition of hydraulic boundaries, and values of hydraulic conductivity, dispersivity and the deep groundwater inflow rate. The overarching conclusion from this study is that the current implementation of the model is robust (the model is largely insensitive to variations in the parameters within the studied ranges) and conservative (the Base Case calculations have a

  8. Solution processed deposition of electron transport layers on perovskite crystal surface-A modeling based study

    Science.gov (United States)

    Mortuza, S. M.; Taufique, M. F. N.; Banerjee, Soumik

    2017-02-01

    The power conversion efficiency (PCE) of planar perovskite solar cells (PSCs) has reached up to ∼20%. However, structural and chemicals defects that lead to hysteresis in the perovskite based thin film pose challenges. Recent work has shown that thin films of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) deposited on the photo absorption layer, using solution processing techniques, minimize surface pin holes and defects thereby increasing the PCE. We developed and employed a multiscale model based on molecular dynamics (MD) and kinetic Monte Carlo (kMC) to establish a relationship between deposition rate and surface coverage on perovskite surface. The MD simulations of PCBMs dispersed in chlorobenzene, sandwiched between (110) perovskite substrates, indicate that PCBMs are deposited through anchoring of the oxygen atom of carbonyl group to the exposed lead (Pb) atom of (110) perovskite surface. Based on rates of distinct deposition events calculated from MD, kMC simulations were run to determine surface coverage at much larger time and length scales than accessible by MD alone. Based on the model, a generic relationship is established between deposition rate of PCBMs and surface coverage on perovskite crystal. The study also provides detailed insights into the morphology of the deposited film.

  9. Transport of Substances on Different Stages of Processes Initiated by Free Fallen Drop Impact on Surface of Quiescent Water

    Science.gov (United States)

    Ilyinykh, A. Yu.

    2012-04-01

    Collision of a free fallen drop with a surface of quiescent layer of water initiates a sequence of processes including initial shock, formation of cavern and crown with a chevron edge emitted small water drops, wide central trough surrounding by a train of running surface circular capillary waves, splash, secondary cavern collapsing with a streamer discharge and gradual decal of all disturbances. Fine structure of the drop splashes and transport of substances carrying by the drop inside accepting target fluid are studied by methods of direct registering of flow images by fast video- and photo cameras. Different directions of observations were realized that are side, top and bottom view of flow patterns. Flow patterns produced by clean and coloured water, alcohol (changing the surface tension) and oil drops were investigated. Attention was concentrated on small scale processes dynamics studying which produce fast variations of water surface shapes with sharp local irregularities. Shapes and textures of craters and surrounding rim surfaces as well as coloured filaments of a drop substance inside the fluid body were registered and analyzed. Two groups of flows with relatively large scales defined by the drop diameter and very fine scales were identified. It is supposed that short living and fast changing flow components are result of strong short-acting forces impact. Their manifestations depend on surface tension on the boundaries fluid-fluid and fluid-air. Effects of surface tension gradients on the drop dye propagation pattern are also demonstrated and discussed. Experiments were performed on set-up USU "HPC IPMec RAS" under support of Ministry of Education and Science RF (Goscontract No. 16.518.11.7059).

  10. NASA Langley's Formal Methods Research in Support of the Next Generation Air Transportation System

    Science.gov (United States)

    Butler, Ricky W.; Munoz, Cesar A.

    2008-01-01

    This talk will provide a brief introduction to the formal methods developed at NASA Langley and the National Institute for Aerospace (NIA) for air traffic management applications. NASA Langley's formal methods research supports the Interagency Joint Planning and Development Office (JPDO) effort to define and develop the 2025 Next Generation Air Transportation System (NGATS). The JPDO was created by the passage of the Vision 100 Century of Aviation Reauthorization Act in Dec 2003. The NGATS vision calls for a major transformation of the nation s air transportation system that will enable growth to 3 times the traffic of the current system. The transformation will require an unprecedented level of safety-critical automation used in complex procedural operations based on 4-dimensional (4D) trajectories that enable dynamic reconfiguration of airspace scalable to geographic and temporal demand. The goal of our formal methods research is to provide verification methods that can be used to insure the safety of the NGATS system. Our work has focused on the safety assessment of concepts of operation and fundamental algorithms for conflict detection and resolution (CD&R) and self- spacing in the terminal area. Formal analysis of a concept of operations is a novel area of application of formal methods. Here one must establish that a system concept involving aircraft, pilots, and ground resources is safe. The formal analysis of algorithms is a more traditional endeavor. However, the formal analysis of ATM algorithms involves reasoning about the interaction of algorithmic logic and aircraft trajectories defined over an airspace. These trajectories are described using 2D and 3D vectors and are often constrained by trigonometric relations. Thus, in many cases it has been necessary to unload the full power of an advanced theorem prover. The verification challenge is to establish that the safety-critical algorithms produce valid solutions that are guaranteed to maintain separation

  11. Quantum transport equation for systems with rough surfaces and its application to ultracold neutrons in a quantizing gravity field

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, M.; Meyerovich, A. E., E-mail: Alexander-Meyerovich@uri.edu [University of Rhode Island, Department of Physics (United States)

    2014-12-15

    We discuss transport of particles along random rough surfaces in quantum size effect conditions. As an intriguing application, we analyze gravitationally quantized ultracold neutrons in rough waveguides in conjunction with GRANIT experiments (ILL, Grenoble). We present a theoretical description of these experiments in the biased diffusion approximation for neutron mirrors with both one- and two-dimensional (1D and 2D) roughness. All system parameters collapse into a single constant which determines the depletion times for the gravitational quantum states and the exit neutron count. This constant is determined by a complicated integral of the correlation function (CF) of surface roughness. The reliable identification of this CF is always hindered by the presence of long fluctuation-driven correlation tails in finite-size samples. We report numerical experiments relevant for the identification of roughness of a new GRANIT waveguide and make predictions for ongoing experiments. We also propose a radically new design for the rough waveguide.

  12. The Helium Field Effect Transistor (II): Gated Transport of Surface-State Electrons Through Micro-constrictions

    Science.gov (United States)

    Shaban, F.; Ashari, M.; Lorenz, T.; Rau, R.; Scheer, E.; Kono, K.; Rees, D. G.; Leiderer, P.

    2016-11-01

    We present transport measurements of surface-state electrons on liquid helium films in confined geometry. The measurements are taken using split-gate devices similar to a field effect transistor. The number of electrons passing between the source and drain areas of the device can be precisely controlled by changing the length of the voltage pulse applied to the gate electrode. We find evidence that the effective driving potential depends on electron-electron interactions, as well as the electric field applied to the substrate. Our measurements indicate that the mobility of electrons on helium films can be high and that microfabricated transistor devices allow electron manipulation on length scales close to the interelectron separation. Our experiment is an important step toward investigations of surface-state electron properties at much higher densities, for which the quantum melting of the system to a degenerate Fermi gas should be observed.

  13. Effect of low-concentration rhamnolipid on transport of Pseudomonas aeruginosa ATCC 9027 in an ideal porous medium with hydrophilic or hydrophobic surfaces.

    Science.gov (United States)

    Zhong, Hua; Liu, Guansheng; Jiang, Yongbing; Brusseau, Mark L; Liu, Zhifeng; Liu, Yang; Zeng, Guangming

    2016-03-01

    The success of effective bioaugmentation processes for remediation of soil and groundwater contamination requires effective transport of the injected microorganisms in the subsurface environment. In this study, the effect of low concentrations of monorhamnolipid biosurfactant solutions on transport of Pseudomonas aeruginosa in an ideal porous medium (glass beads) with hydrophilic or hydrophobic surfaces was investigated by conducting miscible-displacement experiments. Transport behavior was examined for both glucose-grown and hexadecane-grown cells, with low and high surface hydrophobicity, respectively. A clean-bed colloid deposition model was used for determination of deposition rate coefficients. Results show that cells with high surface hydrophobicity exhibit greater retention than cells with low surface hydrophobicity. Rhamnolipid affects cell transport primarily by changing cell surface hydrophobicity, with an additional minor effect by increasing solution ionic strength. There is a good linear relation between k and rhamnolipid-regulated cell surface hydrophobicity presented as bacterial-adhesion-to-hydrocarbon (BATH) rate of cells (R(2)=0.71). The results of this study show the importance of hydrophobic interaction for transport of bacterial cells in silica-based porous media, and the potential of using low-concentration rhamnolipid solutions for facilitating bacterial transport in bioaugmentation efforts.

  14. Incorporating Logistics in Freight Transport Demand Models: State-of-the-Art and Research Opportunities

    NARCIS (Netherlands)

    Tavasszy, L.A.; Ruijgrok, K.; Davydenko, I.

    2012-01-01

    Freight transport demand is a demand derived from all the activities needed to move goods between locations of production to locations of consumption, including trade, logistics and transportation. A good representation of logistics in freight transport demand models allows us to predict the effects

  15. Prediction of Flow and Solute Transport in Fractured Media: Comparison of Metrics to Describe Effects of Rough Surfaces

    Science.gov (United States)

    Slottke, D.; Ketcham, R. A.; Sharp, J. M.

    2008-05-01

    Fractures dominate fluid flow and transport of solutes when they are open and connected. The prediction of flow through fractured media has implications for development of water resources, petroleum reservoir exploitation, contamination and remediation assessment, and site evaluation for waste repositories. Assessing the impact of surface roughness on fluid flow and solute transport through fractured media from samples on the order of 100 cm2 assumes the existence of a relationship between fracture morphology and discharge that is scale invariant or at least smoothly transformable. Although some studies assume that the length scale at which surface roughness significantly contributes to the discharge through a fracture falls within the size of a typical hand sample, there is a dearth of empirical data supporting an extension of the relationships found at small scales to larger samples. Furthermore, an appropriate metric to describe a fracture volume accurately must be chosen. We compile data from physical flow tests and numerical modeling of two discrete natural fractures of different scales in rhyolitc tuff. The University of Texas HRXCT facility provided computed tomography representations of the fractures that allow analysis of surface roughness and aperture statistics at 0.25mm grid resolution, which form the basis for transmissivity field inputs to numerical models. We show that although a small (10cm2) representative surface can describe roughness, aperture fields are not so well behaved. We compare physical flow test results, modeled flow, and analytical solutions of the cubic law using various methods of assigning a meaningful aperture to illustrate the challenges of accurate modeling of fracture flow without a priori flow information. While a geometric mean aperture of the entire aperture field closely approximates the hydraulic aperture, an arbitrary profile mean aperture has little utility for predictive purposes.

  16. Evolving research directions in Surface Ocean-Lower Atmosphere (SOLAS) science

    NARCIS (Netherlands)

    Law, Cliff S.; Breviere, Emilie; de Leeuw, Gerrit; Garcon, Veronique; Guieu, Cecile; Kieber, David J.; Kontradowitz, Stefan; Paulmier, Aurelien; Quinn, Patricia K.; Saltzman, Eric S.; Stefels, Jacqueline; von Glasow, Roland

    2013-01-01

    This review focuses on critical issues in ocean-atmosphere exchange that will be addressed by new research strategies developed by the international Surface Ocean-Lower Atmosphere Study (SOLAS) research community. Eastern boundary upwelling systems are important sites for CO2 and trace gas emission

  17. Research and development of MRI surface coil for TMJ MR imaging; Modulated Helmholtz surface coil

    Energy Technology Data Exchange (ETDEWEB)

    Kukimoto, Yoshiaki; Kukimoto, Kyoko (Kameda General Hospital, Kamogawa, Chiba (Japan)); Shirakawa, Toyomi

    1989-12-01

    Internal derangements of the temporomandibular joint (TMJ) are a major cause of jaw pain and dysfunction as well as other related clinical symptoms. TMJ diagnosis is the abnormal position and appearance of the disk. Most X-ray-based methods are useful for evaluating bony abnormalities, but their reduced soft-tissue contrast often makes the diagnostic evaluation of TMJ disorders difficult. Magnetic resonance (MR) imaging is a very recent addition to the medical diagnostic of TMJ diseases. MR imaging can produce high-quality tomographic images of greater soft-tissue contrast without ionizing radiation or known biological hazards. MR system was circular type Simens Magnetom 1.5 tesla. Display matrix was 256x256. A Modulated Helmholtz type coil of 17 cm in diameter was developed in Kameda General Hospital in order to increase signal to noise ratio in the area of bilateral TMJs. The distance between two coils was 16-20 cm. The head was placed in supine position in the center of two surface coils. A Modulated Helmholtz type coil: 1. Modulated Helmholtz type coil was used as an emitter and a receiver. 2. Modulated Helmholtz type coil had a pair of 17 cm coils, which were movable according to head width of each patient. 3. MR imaging of bilateral TMJs was taken at once because of no necessity to reset a surfacecoil. 4. It was easy to set positioning of the head. (author).

  18. Electrical-stress-induced transport and surface potential characterizations of metal/ TiO 2/metal planar junctions

    Science.gov (United States)

    Kim, Haeri; Kim, Dong-Wook

    2011-03-01

    Electric-field-induced resistive switching (RS) phenomena in metal oxides have attracted considerable research interest due to their potential use in nonvolatile memory device applications. Intensive investigations have revealed that coupled electron ion dynamics play a key role the RS mechanism. Metal/single crystal junction can be an ideal model system to study how the ionic drift and diffusion can affect the resistance. We investigated transport and local electrical properties of Pt/ Ti O2 single crystal/Ti planar junctions with micron- sized gaps between the electrodes. Scanning Kelvin probe microscopy (SKPM) showed that negative (positive) electrical stress to the Pt electrodes significantly reduced (hardly affected) the Pt/ Ti O2 contact resistance. The SKPM results also revealed that the electrical stress caused alteration of the local work function of Ti O2 . The comparative investigations of the transport and SKPM results suggested that the electrical stress induced redistribution of ions, resulting in the change of the junction resistance.

  19. Collaborative Research: Fundamental studies of plasma control using surface embedded electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Raja, Laxminarayan L. [Univ. of Texas, Austin, TX (United States); PanneerChelvam, PremKumar [Univ. of Texas, Austin, TX (United States); Levko, Dimtry [Univ. of Texas, Austin, TX (United States)

    2016-02-26

    The proposed study will investigate the effect of active electron injection of from electrode surfaces To the best of our knowledge, no such a study has ever been attempted even though it could lead to the formation of whole new classes of plasma based devices and systems. We are motivated by recent articles and simple theory which gives strong reason to believe that embedded electronic devices can be used to exert control over the SEE coefficient of semiconductor surfaces (and maybe other surface types as well). Furthermore, the research will explore how such sub-surface electronic devices can best be used to exert control over an associated plasma.

  20. Research and design of the structure of information support of road transport

    Directory of Open Access Journals (Sweden)

    V. G. Kozlov

    2016-01-01

    Full Text Available The main issue is to study the interaction between the system of road transport and security of its information systems. The mechanism of this interaction is studied only on the basis of studies of the learning process. These two interacting systems through training react to each other. Due to the strong correlation between these two systems offer the development of the basics of management information support to carry out complex, without violating the integrity of the systems. As the methods of research used methods of system analysis and probability theory. The criteria for the study of the interaction of systems: full-scale technological and economic indicators. By the technological parameters include: completeness of use of the system (load, and performance of information security; to full-scale - the cost of labor, energy, materials; to the economic - the cost, payback, profit, profit. The stages of the development of the structure of information support: the definition of objectives; study of the problems and the choice of solution to the problem; agreed solutions (thematic plan; approval of decisions; Management and Implementation; verification of the effectiveness of decisions. Established shortcomings in the existing system of information support of decentralization processes interrelated technical planning; territorial, institutional and administrative divisions of organizations taking interdependent solutions; the lack of control most of the organizations operating information support for road transport; incomplete information of the absolute majority of publishing houses in the needs of motorists; duplication of the work of many publishers. There are two mechanisms of control information management system. Control enhances performance management system, improves the output characteristics of the system.

  1. A putative cell surface receptor for white spot syndrome virus is a member of a transporter superfamily.

    Directory of Open Access Journals (Sweden)

    Huai-Ting Huang

    Full Text Available White spot syndrome virus (WSSV, a large enveloped DNA virus, can cause the most serious viral disease in shrimp and has a wide host range among crustaceans. In this study, we identified a surface protein, named glucose transporter 1 (Glut1, which could also interact with WSSV envelope protein, VP53A. Sequence analysis revealed that Glut1 is a member of a large superfamily of transporters and that it is most closely related to evolutionary branches of this superfamily, branches that function to transport this sugar. Tissue tropism analysis showed that Glut1 was constitutive and highly expressed in almost all organs. Glut1's localization in shrimp cells was further verified and so was its interaction with Penaeus monodon chitin-binding protein (PmCBP, which was itself identified to interact with an envelope protein complex formed by 11 WSSV envelope proteins. In vitro and in vivo neutralization experiments using synthetic peptide contained WSSV binding domain (WBD showed that the WBD peptide could inhibit WSSV infection in primary cultured hemocytes and delay the mortality in shrimps challenged with WSSV. These findings have important implications for our understanding of WSSV entry.

  2. Tracking of magnetic flux concentrations over a five-day observation, and an insight into surface magnetic flux transport

    Directory of Open Access Journals (Sweden)

    Iida Yusuke

    2016-01-01

    Full Text Available The solar dynamo problem is the question of how the cyclic variation in the solar magnetic field is maintained. One of the important processes is the transport of magnetic flux by surface convection. To reveal this process, the dependence of the squared displacement of magnetic flux concentrations on the elapsed time is investigated in this paper via a feature-recognition technique and a continual five-day magnetogram. This represents the longest time scale over which a satellite observation has ever been performed for this problem. The dependence is found to follow a power law and differ significantly from that of diffusion transport. Furthermore, there is a change in the behavior at a spatial scale of 103.8 km. A super-diffusion behavior with an index of 1.4 is found at smaller scales, while changing to a sub-diffusion behavior with an index of 0.6 on larger ones. We interpret this difference in the transport regime as coming from the network-flow pattern.

  3. Transport properties governed by surface barriers in Bi2Sr2CaCu2O8

    Science.gov (United States)

    Fuchs, Dan T.; Zeldov, Eli; Rappaport, Michael; Tamegai, Tsuyoshi; Ooi, Shuuichi; Shtrikman, Hadas

    1998-01-01

    One of the most common investigation techniques of type-II superconductors is the transport measurement, in which an electrical current is applied to a sample and the corresponding resistance is measured as a function of temperature and magnetic field. At temperatures well below the critical temperature, Tc, the resistance of a superconductor is usually immeasurably low. But at elevated temperatures and fields, in the so-called vortex liquid phase, a substantial linear resistance is observed. In this dissipative state, which in anisotropic high-temperature superconductors like Bi2Sr2CaCu2O8 may occupy most of the mixed-state phase diagram, the transport current is usually assumed to flow uniformly across the sample as in a normal metal. To test this assumption, we have devised a measurement approach which allows determination of the flow pattern of the transport current across the sample. The surprising result is that, in Bi2Sr2CaCu2O8 crystals, most of the current flows at the edges of the sample rather than in the bulk, even in the highly resistive state, due to the presence of strong surface barriers. This finding has significant implications for the interpretation of existing resistivity data and may be of importance for the development of high-temperature superconducting wires and tapes.

  4. Tracking of magnetic flux concentrations over a five-day observation and an insight into surface magnetic flux transport

    CERN Document Server

    Iida, Y

    2016-01-01

    The solar dynamo problem is the question of how the cyclic variation in the solar magnetic field is maintained. One of the important processes is the transport of magnetic flux by surface convection. To reveal this process, the dependence of the squared displacement of magnetic flux concentrations upon the elapsed time is investigated in this paper via a feature-recognition technique and a continual five-day magnetogram. This represents the longest time scale over which a satellite observation has ever been performed for this problem. The dependence is found to follow a power-law and differ significantly from that of diffusion transport. Furthermore there is a change in the behavior at a spatial scale of 10^{3.8} km. A super-diffusion behavior with an index of 1.4 is found on smaller scales, while changing to a sub-diffusion behavior with an index of 0.6 on larger ones. I interpret this difference in the transport regime as coming from the network-flow pattern.

  5. Circular dichroism and superdiffusive transport at the surface of BiTeI.

    Science.gov (United States)

    Mauchain, J; Ohtsubo, Y; Hajlaoui, M; Papalazarou, E; Marsi, M; Taleb-Ibrahimi, A; Faure, J; Kokh, K A; Tereshchenko, O E; Eremeev, S V; Chulkov, E V; Perfetti, L

    2013-09-20

    We investigate the electronic states of BiTeI after the optical pumping with circularly polarized photons. Our data show that photoexcited electrons reach an internal thermalization within 300 fs of the arrival of the pump pulse. Instead, the dichroic contrast generated by the circularly polarized light relaxes on a time scale shorter than 80 fs. This result implies that orbital and spin polarization created by the circular pump pulse rapidly decays via manybody interaction. The persistent dichroism at longer delay times is due to the helicity dependence of superdiffussive transport. We ascribe it to the lack of inversion symmetry in an electronic system far from equilibrium conditions.

  6. Soil surface searching and transport of Euphorbia characias seeds by ants

    Science.gov (United States)

    Espadaler, Xavier; Gómez, Crisanto

    The intensity of exploring the soil surface by ants was studied for the four species involved in the dispersal and predation of seeds of the West-Mediterranean myrmecochorous plant Euphorbia characias. During the dehiscence period (June) the whole soil surface is sccanned in 43 minutes. Not all ants that find a seed take it to the nest. For the four ant species studied ( Pheidole pallidula, Aphaenogaster senilis, Tapinoma nigerrimum, Messor barbarus) the proportion of ants that finally take the seed is 67.6%. In spite of this, the high level of soil surface searching explains the rather short time that seeds remain on the soil before being removed. The presence of an elaiosome is a key element in the outcome of the ant-seed interaction: a seed with elaiosome has a seven-fold increase in probability of being taken to the nest if found by a non-granivorous ant. The predator-avoidance hypothesis for myrmecochory is supported.

  7. The Effect of Diffusional Transport and Surface Catalysis on the Aerothermodynamic Heating for Martian Atmospheric Entry

    Science.gov (United States)

    Henline, William D.; Papadopoulos, Periklis; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    For the reentry heating of 70-degree blunt sphere-cones entering Mars at velocities in excess of 6 km/sec, a study was performed to determine the magnitude of both convective and catalytic heating on the cone forebody. Case studies of the peak heating conditions for the current NASA Mars Pathfinder entry probe, as well as the peak heating conditions of the proposed NASA Mars 2001 aerobraking orbiter mission were performed. Since the actual behavior of the chemical recombination of Mars atmosphere hypersonic shock layer species on heat shield materials is not known, and no experimental studies of any consequence have been done to determine surface reaction rates for the CO2 system, a parametric analysis of various reaction schemes and surface catalytic mechanistic models was performed. In many cases the actual Mars entry probe will have a heat shield composed of an ablative material which can either partially or completely preclude the existence of catalytic surface recombination phenomena. The extent of this blockage effect has not been examined at this time and is not considered in this effort. Instead only non-ablative computations are performed to separately evaluate the full extent of the surface catalysis and related diffusional phenomena. Parametric studies include peak heating point comparisons of non-catalytic, partially catalytic and fully catalytic total surface heat transfer for three difference surface recombination catalytic mechanisms (with and without simultaneous CO + O and O + O recombination) as well as with different species diffusion models. Diffusion model studies include constant Schmidt number (equal diffusivities) and the bifurcation, approximate multi-component diffusion model. Since the gas phase reaction kinetics for the Mars CO2 based atmosphere have also not been validated, the effect of two different (fast and slow) sets of gas kinetics on heat transfer is presented.

  8. Efficient Coupling and Transport of a Surface Plasmon at 780 nm in a Gold Nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2015-08-28

    We studied plasmonic nanostructures in single-crystal gold with scanning electron and femtosecond photoemission electron microscopies. We designed an integrated laser coupling and nanowire waveguide structure by focused ion beam lithography in single-crystal gold flakes. The photoemission results show that the laser field is efficiently coupled into a propagating surface plasmon by a simple hole structure and propagates efficiently in an adjacent nano-bar waveguide. A strong local field is created by the propagating surface plasmon at the nano-bar tip. A similar structure, with a decreased waveguide width and thickness, displayed significantly more intense photoemission indicating enhanced local electric field at the sharper tip.

  9. Electronic transport through Si nanowires: Role of bulk and surface disorder

    DEFF Research Database (Denmark)

    Markussen, Troels; Rurali, R.; Brandbyge, Mads

    2006-01-01

    on the situation a preferable method can be identified. Several numerical results are presented to illustrate the relative merits of the two methods. Our calculations of relaxed atomic structures and their conductance properties are based on density functional theory without introducing adjustable parameters. Two...... specific models of disorder are considered: Unpassivated, surface reconstructed SiNW's are perturbed by random on-site (Anderson) disorder whereas defects in hydrogen passivated wires are introduced by randomly removed H atoms. The unpassivated wires are very sensitive to disorder in the surface whereas...

  10. Transport of a nematicide in surface and ground waters in a farmed tropical catchment with volcanic substratum

    Science.gov (United States)

    Charlier, J.-B.; Cattan, P.; Voltz, M.; Moussa, R.

    2009-04-01

    Assessment of water-pollution risks in agricultural regions requires studying pesticide transport processes in soil and water compartments at the catchment scale. In tropical regions, banana (Musa spp.) plantations are located in zones with abundant rainfalls and soils with high infiltration rates, which lead to washout and leaching of soil-applied pesticides, causing severe diffuse pollution of water resources. The aim of this paper is to determine how the nematicide cadusafos [S,S-di-sec-butyl O-ethyl phosphorodithioate], used in banana plantations, contaminates water and soils at the two scales of subcatchment and catchment. The study site was a small banana-growing catchment on the tropical volcanic island of Guadeloupe in the Caribbean (FWI). The catchment is located in pedoclimatic conditions where rainfall is abundant (> 4000 mm/year), and soil permeable (saturated hydraulic conductivity of Andosol Ks > 30 mm/h). Two campaigns of nematicide application were conducted, one in 2003 over 40% of the catchment and one in 2006 over 12%. For 100 days after application, we monitored the surface water and groundwater flows and the cadusafos concentrations in the soil and in surface and ground waters in a 2400 m² subcatchment and a 17.8 ha catchment. The results show that at the subcatchment scale the high retention in the A horizon of the soil limited the transport of cadusafos by runoff, whereas the lower retention of the molecule in the B horizon favoured percolation towards the shallow groundwater. The contamination levels of surface water, as well as shallow and deep groundwaters, reflected the geological structure of the Féfé catchment: i.e. a shallow aquifer in the most recent volcanic deposits that is rapidly exposed to pollution and a deeper aquifer that is relatively protected from the pollution coming from the treated fields. Comparing the losses of cadusafos at the subcatchment and at the catchment scales revealed that the nematicide re-infiltrated in

  11. Turbulent coherent-structure dynamics in a natural surface storage zone: Mechanisms of mass and momentum transport in rivers

    Science.gov (United States)

    Escauriaza, Cristian; Sandoval, Jorge; Mignot, Emmanuel; Mao, Luca

    2016-11-01

    Turbulent flows developed in surface storage zones (SSZ) in rivers control many physical and biogeochemical processes of contaminants in the water. These regions are characterized by low velocities and long residence times, which favor particle deposition, nutrient uptake, and flow interactions with reactive sediments. The dynamics of the flow in SSZ is driven by a shear layer that induces multiple vortical structures with a wide range of temporal and spatial scales. In this work we study the flow in a lateral SSZ of the Lluta River, a high-altitude Andean stream (4,000 masl), with a Re=45,800. We describe the large-scale turbulent coherent structures using field measurements and 3D numerical simulations. We measure the bed topography, instantaneous 3D velocities at selected points, the mean 2D free-surface velocity field, and arsenic concentration in the sediment. Numerical simulations of the flow are also performed using a DES turbulence model. We focus on the mass and momentum transport processes, analyzing the statistics of mass exchange and residence times in the SSZ. With this information we provide new insights on the flow and transport processes between the main channel and the recirculating region in natural conditions. Supported by Fondecyt 1130940.

  12. The effects of the accuracy of the atmospheric forcings on the prediction of the sea surface transport in coastal areas.

    Science.gov (United States)

    Cucco, Andrea; Quattrocchi, Giovanni; Satta, Andrea; Antognarelli, Fabio; della Valle, Antonio; De Biasio, Francesco; Cadau, Enrico; Zecchetto, Stefano; Umgiesser, Georg

    2015-04-01

    In the framework of the Italian flagship project RITMARE (http://www.ritmare.it/en/) an Operational Oceanography Systems (OOS hereafter) based on high resolution 3D hydrodynamic model has been developed for the Oristano Gulf (Sardinia, Italy), with the aim of making short term predictions of water currents and pollutant transport. Atmospheric data provided by the SKIRON meteorological model system (http://forecast.uoa.gr/) were used to make the predictions. In order to asses the quality of the wind field adopted to force the hydrodynamic model, a coastal wind measuring system (WMS hereafter) was developed. The WMS is composed by five three-components anemometers located along the Gulf coasts, which provide hourly and operationally wind measurements. These data are then used operationally to derive high resolution wind fields over the entire Gulf and surrounding coastal areas. The modelled wind data have been compared with the measured ones and the meteorological model accuracy estimated. A set of lagrangian buoys were deployed within the Gulf to measure the sea surface transport due to the main local wind regimes. The OOS were used to reproduce the paths followed by each lagrangian buoy using as forcing conditions both the wind fields measured by the local WMS and the predicted ones. Therefore the effects of the atmospheric forcing quality on predicting the surface hydrodynamics at coastal scale were determined.

  13. Ab-Initio Modelling Of Surface Site Reactivity And Fluid Transport In Clay Minerals Case Study: Pyrophyllite

    Energy Technology Data Exchange (ETDEWEB)

    Churakov, S.V

    2005-03-01

    Pyrophyllite, Al{sub 2}[Si{sub 4}O{sub 10}](OH){sub 2}, is the simplest structural prototype for 2:1 dioctahedral phyllosilicate. Because the net electric charge in pyrophyllite is zero, it is the best candidate for investigating the non electrostatic contribution to sorption and transport phenomena in clays. Using ab-initio simulations, we have investigated the reactivity and structure of the water-solid interface on the basal plane and edge sites of pyrophyllite. The calculations predict slightly hydrophobic behaviour of the basal plane. For the high water coverage (100), (110) and (-110), lateral facets have a lower energy than for the (010), (130) and (-130) surfaces. Analysis of the surface reactivity reveals that the =Al-OH groups are most easily protonated on the (010), (130) and (-130) facets. The =Al-O-Si= sites will be protonated on the (100), (130), (110), (-110) and (-130) surfaces. The =Al-OH{sub 2} complexes are more easily de-protonated than the =Si-OH and =Al-OH sites. A spontaneous, reversible exchange of the protons between the solution and the edge sites has been observed in ab-initio molecular dynamics simulations at 300 K. Such near-surface proton diffusion may result in a significant contribution to the diffusion coefficients measured in neutron scattering experiments. (author)

  14. Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves

    Science.gov (United States)

    Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

    1992-01-01

    The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

  15. Electrowetting actuated microfluidic transport in surface grooves with triangular cross section.

    Science.gov (United States)

    Barman, Jitesh; Swain, Digendranath; Law, Bruce M; Seemann, Ralf; Herminghaus, Stephan; Khare, Krishnacharya

    2015-01-27

    Liquids show different static wetting morphologies in open triangular grooves depending upon the wedge angle (ψ) of the groove and the liquid contact angle (θ) with the substrate. Switching between different morphologies can be achieved either by varying the contact angle of the liquid or by changing the wedge angle of the groove. In the present work we manipulate the apparent contact angle of a liquid by electrowetting to switch between liquid morphologies, from droplet to filament, to achieve microfluidic transport of the liquid into open triangular grooves. The static length of liquid filaments in grooves is analyzed as a function of applied voltage for different applied ac frequencies. The dynamic advancement of the filament lengths in grooves is analyzed as a function of time for different applied voltages for two different liquids: first with contact angle greater than the wedge angle and second with contact angle smaller than the wedge angle. Later an exact electrical model is derived to explain the liquid transport in triangular grooves actuated by electrowetting which includes the precise geometry of the liquid morphology.

  16. Microstructuring of thermo-mechanically highly stressed surfaces final report of the DFG research group 576

    CERN Document Server

    Rienäcker, Adrian; Knoll, Gunter; Bach, Friedrich-Wilhelm; Maier, Hans; Reithmeier, Eduard; Dinkelacker, Friedrich

    2015-01-01

    This contributed volume presents the final research results of the DFG Research Group 576, which is a joint initiative of five different institutes of the Leibniz Universität Hannover and the Universität Kassel, Germany. The research of the DFG Research Group 576 focuses on improving the tribological behavior of thermomechanically highly stressed surfaces, particularly on cylinder liner for combustion engines. The target audience primarily comprises researchers and experts in the field but the book may also be beneficial for graduate students who want to specialize in the field.

  17. FOB-SH: Fragment orbital-based surface hopping for charge carrier transport in organic and biological molecules and materials

    Science.gov (United States)

    Spencer, J.; Gajdos, F.; Blumberger, J.

    2016-08-01

    We introduce a fragment orbital-based fewest switches surface hopping method, FOB-SH, designed to efficiently simulate charge carrier transport in strongly fluctuating condensed phase systems such as organic semiconductors and biomolecules. The charge carrier wavefunction is expanded and the electronic Hamiltonian constructed in a set of singly occupied molecular orbitals of the molecular sites that mediate the charge transfer. Diagonal elements of the electronic Hamiltonian (site energies) are obtained from a force field, whereas the off-diagonal or electronic coupling matrix elements are obtained using our recently developed analytic overlap method. We derive a general expression for the exact forces on the adiabatic ground and excited electronic state surfaces from the nuclear gradients of the charge localized electronic states. Applications to electron hole transfer in a model ethylene dimer and through a chain of ten model ethylenes validate our implementation and demonstrate its computational efficiency. On the larger system, we calculate the qualitative behaviour of charge mobility with change in temperature T for different regimes of the intermolecular electronic coupling. For small couplings, FOB-SH predicts a crossover from a thermally activated regime at low temperatures to a band-like transport regime at higher temperatures. For higher electronic couplings, the thermally activated regime disappears and the mobility decreases according to a power law. This is interpreted by a gradual loss in probability for resonance between the sites as the temperature increases. The polaron hopping model solved for the same system gives a qualitatively different result and underestimates the mobility decay at higher temperatures. Taken together, the FOB-SH methodology introduced here shows promise for a realistic investigation of charge carrier transport in complex organic, aqueous, and biological systems.

  18. Laser surface micro-/nano-structuring by a simple transportable micro-sphere lens array

    NARCIS (Netherlands)

    Sedao, X.; Derrien, T.J.Y.; Romer, G.W.R.B.E.; Pathiraj, B.; Huis in 't Veld, A.J.

    2012-01-01

    A micro-sphere array optic was employed for laser surface micro-structuring. This array optic consists of a hexagonally close-packed monolayer of silica micro-spheres. It was organized through a self-assembly process and held together on a glass support, without using any adhesives. The array assemb

  19. Ultrahigh-frequency surface acoustic wave generation for acoustic charge transport in silicon

    NARCIS (Netherlands)

    Büyükköse, S.; Vratzov, B.; van der Veen, Johan (CTIT); Santos, P.V.; van der Wiel, Wilfred Gerard

    2013-01-01

    We demonstrate piezo-electrical generation of ultrahigh-frequency surface acoustic waves on silicon substrates, using high-resolution UV-based nanoimprint lithography, hydrogen silsequioxane planarization, and metal lift-off. Interdigital transducers were fabricated on a ZnO layer sandwiched between

  20. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

    2002-01-01

    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores t

  1. Laser surface micro-/nano-structuring by a simple transportable micro-sphere lens array

    NARCIS (Netherlands)

    Sedao, X.; Derrien, T.J.Y.; Romer, G.W.R.B.E.; Pathiraj, B.; Huis in 't Veld, A.J.

    2012-01-01

    A micro-sphere array optic was employed for laser surface micro-structuring. This array optic consists of a hexagonally close-packed monolayer of silica micro-spheres. It was organized through a self-assembly process and held together on a glass support, without using any adhesives. The array

  2. Phosphate availability in the soil-root system: integration of oxide surface chemistry, transport and uptake.

    NARCIS (Netherlands)

    Geelhoed, J.S.

    1998-01-01

    A study is presented on the adsorption of phosphate on goethite, the interaction of phosphate with other adsorbing ions at the goethite surface, and the resulting availability of phosphate to plants. The plant-availability of sorbed phosphate was determined from phosphorus uptake of plants growing o

  3. Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

    NARCIS (Netherlands)

    Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

    2002-01-01

    Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores t

  4. Self-assembled monolayers based spintronics: from ferromagnetic surface functionalization to spin-dependent transport.

    Science.gov (United States)

    Tatay, Sergio; Galbiati, Marta; Delprat, Sophie; Barraud, Clément; Bouzehouane, Karim; Collin, Sophie; Deranlot, Cyrile; Jacquet, Eric; Seneor, Pierre; Mattana, Richard; Petroff, Frédéric

    2016-03-09

    Chemically functionalized surfaces are studied for a wide range of applications going from medicine to electronics. Whereas non-magnetic surfaces have been widely studied, functionalization of magnetic surfaces is much less common and has almost never been used for spintronics applications. In this article we present the functionalization of La2/3Sr1/3MnO3, a ferromagnetic oxide, with self-assembled monolayers for spintronics. La2/3Sr1/3MnO3 is the prototypical half-metallic manganite used in spintronics studies. First, we show that La2/3Sr1/3MnO3 can be functionalized by alkylphosphonic acid molecules. We then emphasize the use of these functionalized surfaces in spintronics devices such as magnetic tunnel junctions fabricated using a nano-indentation based lithography technique. The observed exponential increase of tunnel resistance as a function of alkyl chain length is a direct proof of the successful connection of molecules to ferromagnetic electrodes. For all alkyl chains studied we obtain stable and robust tunnel magnetoresistance, with effects ranging from a few tens to 10 000%. These results show that functionalized electrodes can be integrated in spintronics devices and open the door to a molecular engineering of spintronics.

  5. Microscopic droplet formation and energy transport analysis of condensation on scalable superhydrophobic nanostructured copper oxide surfaces.

    Science.gov (United States)

    Li, GuanQiu; Alhosani, Mohamed H; Yuan, ShaoJun; Liu, HaoRan; Ghaferi, Amal Al; Zhang, TieJun

    2014-12-01

    Utilization of nanotechnologies in condensation has been recognized as one opportunity to improve the efficiency of large-scale thermal power and desalination systems. High-performance and stable dropwise condensation in widely-used copper heat exchangers is appealing for energy and water industries. In this work, a scalable and low-cost nanofabrication approach was developed to fabricate superhydrophobic copper oxide (CuO) nanoneedle surfaces to promote dropwise condensation and even jumping-droplet condensation. By conducting systematic surface characterization and in situ environmental scanning electron microscope (ESEM) condensation experiments, we were able to probe the microscopic formation physics of droplets on irregular nanostructured surfaces. At the early stages of condensation process, the interfacial surface tensions at the edge of CuO nanoneedles were found to influence both the local energy barriers for microdroplet growth and the advancing contact angles when droplets undergo depinning. Local surface roughness also has a significant impact on the volume of the condensate within the nanostructures and overall heat transfer from the vapor to substrate. Both our theoretical analysis and in situ ESEM experiments have revealed that the liquid condensate within the nanostructures determines the amount of the work of adhesion and kinetic energy associated with droplet coalescence and jumping. Local and global droplet growth models were also proposed to predict how the microdroplet morphology within nanostructures affects the heat transfer performance of early-stage condensation. Our quantitative analysis of microdroplet formation and growth within irregular nanostructures provides the insight to guide the anodization-based nanofabrication for enhancing dropwise and jumping-droplet condensation performance.

  6. Potential problems with environmental sound barriers when used in mitigating surface transportation noise.

    Science.gov (United States)

    Arenas, Jorge P

    2008-11-01

    The public, increasingly well-informed about the problem of excessive noise, is taking actions for the development of new transport infrastructure projects and improvement of existing infrastructure. In addition, many countries have implemented mandatory Environmental Impact Assessment procedures. As a result, the construction of sound barriers has become a common measure, which can be used by an agency to mitigate potentially significant noise impacts. A sound barrier, eventually, will become part of the surrounding landscape and could be a cause of impact for ecosystems, the road users and those who live alongside the road. Basically, this article discusses these potential effects in the context of environmental assessment procedures. In addition, results of a pilot survey conducted at a residential area affected by the construction of a barrier are presented. Although most residents felt that sleeping conditions improved after the barrier was built, most important negative reactions are the loss of sunlight and visual impact.

  7. Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins

    Science.gov (United States)

    Gregoire, Caroline; Capel, Paul D.; Coupe, Richard H.; Kalkhoff, Stephen J.

    2011-01-01

    BACKGROUND: Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used widely throughout the world in the production of many crops and is heavily used on soybeans, corn and cotton. Glyphosate is used in almost all agricultural areas of the United States, and the agricultural use of glyphosate has increased from less than 10 000 Mg in 1992 to more than 80 000 Mg in 2007. The greatest intensity of glyphosate use is in the midwestern United States, where applications are predominantly to genetically modified corn and soybeans. In spite of the increase in usage across the United States, the characterization of the transport of glyphosate and its degradate aminomethylphosphonic acid (AMPA) on a watershed scale is lacking.

  8. Nanofluidic Transport over a Curved Surface with Viscous Dissipation and Convective Mass Flux

    Science.gov (United States)

    Mehmood, Zaffar; Iqbal, Z.; Azhar, Ehtsham; Maraj, E. N.

    2017-03-01

    This article is a numerical investigation of boundary layer flow of nanofluid over a bended stretching surface. The study is carried out by considering convective mass flux condition. Contribution of viscous dissipation is taken into the account along with thermal radiation. Suitable similarity transformations are employed to simplify the system of nonlinear partial differential equations into a system of nonlinear ordinary differential equations. Computational results are extracted by means of a shooting method embedded with a Runge-Kutta Fehlberg technique. Key findings include that velocity is a decreasing function of curvature parameter K. Moreover, Nusselt number decreases with increase in curvature of the stretching surface while skin friction and Sherwood number enhance with increase in K.

  9. Volatile transport on inhomogeneous surfaces: II. Numerical calculations (VT3D)

    CERN Document Server

    Young, Leslie A

    2015-01-01

    Several distant icy worlds have atmospheres that are in vapor-pressure equilibrium with their surface volatiles, including Pluto, Triton, and, probably, several large KBOs near perihelion. Studies of the volatile and thermal evolution of these have been limited by computational speed, especially for models that treat surfaces that vary with both latitude and longitude. In order to expedite such work, I present a new numerical model for the seasonal behavior of Pluto and Triton which (i) uses initial conditions that improve convergence, (ii) uses an expedient method for handling the transition between global and non-global atmospheres, (iii) includes local conservation of energy and global conservation of mass to partition energy between heating, conduction, and sublimation or condensation, (iv) uses time-stepping algorithms that ensure stability while allowing larger timesteps, and (v) can include longitudinal variability. This model, called VT3D, has been used in Young (2012), Young (2013), Olkin et al. (201...

  10. Nanofluidic transport over a curved surface with viscous dissipation and convective mass flux

    Energy Technology Data Exchange (ETDEWEB)

    Mehmood, Zaffar; Iqbal, Z.; Azhar, Ehtsham; Maraj, E.N. [HITEC Univ., Taxila (Pakistan). Dept. of Mathematics

    2017-06-01

    This article is a numerical investigation of boundary layer flow of nanofluid over a bended stretching surface. The study is carried out by considering convective mass flux condition. Contribution of viscous dissipation is taken into the account along with thermal radiation. Suitable similarity transformations are employed to simplify the system of nonlinear partial differential equations into a system of nonlinear ordinary differential equations. Computational results are extracted by means of a shooting method embedded with a Runge-Kutta Fehlberg technique. Key findings include that velocity is a decreasing function of curvature parameter K. Moreover, Nusselt number decreases with increase in curvature of the stretching surface while skin friction and Sherwood number enhance with increase in K.

  11. The Small Aircraft Transportation System (SATS), Higher Volume Operations (HVO) Concept and Research

    Science.gov (United States)

    Baxley, B.; Williams, D.; Consiglio, M.; Adams, C.; Abbott, T.

    2005-01-01

    The ability to conduct concurrent, multiple aircraft operations in poor weather at virtually any airport offers an important opportunity for a significant increase in the rate of flight operations, a major improvement in passenger convenience, and the potential to foster growth of operations at small airports. The Small Aircraft Transportation System, (SATS) Higher Volume Operations (HVO) concept is designed to increase capacity at the 3400 non-radar, non-towered airports in the United States where operations are currently restricted to one-in/one-out procedural separation during low visibility or ceilings. The concept s key feature is that pilots maintain their own separation from other aircraft using air-to-air datalink and on-board software within the Self-Controlled Area (SCA), an area of flight operations established during poor visibility and low ceilings around an airport without Air Traffic Control (ATC) services. While pilots self-separate within the SCA, an Airport Management Module (AMM) located at the airport assigns arriving pilots their sequence based on aircraft performance, position, winds, missed approach requirements, and ATC intent. The HVO design uses distributed decision-making, safe procedures, attempts to minimize pilot and controller workload, and integrates with today's ATC environment. The HVO procedures have pilots make their own flight path decisions when flying in Instrument Metrological Conditions (IMC) while meeting these requirements. This paper summarizes the HVO concept and procedures, presents a summary of the research conducted and results, and outlines areas where future HVO research is required. More information about SATS HVO can be found at http://ntrs.nasa.gov.

  12. New experimental trends for phosphoinositides research on ion transporter/channel regulation.

    Science.gov (United States)

    Mori, Masayuki X; Inoue, Ryuji

    2014-01-01

    Phosphoinositides(4,5)-bisphosphates [PI(4,5)P2] critically controls membrane excitability, the disruption of which leads to pathophysiological states. PI(4,5)P2 plays a primary role in regulating the conduction and gating properties of ion channels/transporters, through electrostatic and hydrophobic interactions that allow direct associations. In recent years, the development of many molecular tools have brought deep insights into the mechanisms underlying PI(4,5)P2-mediated regulation. This review summarizes the methods currently available to manipulate the cell membrane PI(4,5)P2 level including pharmacological interventions as well as newly designed molecular tools. We concisely introduce materials and experimental designs suitable for the study of PI(4,5)P2-mediated regulation of ion-conducting molecules, in order to assist researchers who are interested in this area. It is our further hope that the knowledge introduced in this review will help to promote our understanding about the pathology of diseases such as cardiac arrhythmias, bipolar disorders, and Alzheimer's disease which are somehow associated with a disruption of PI(4,5)P2 metabolism.

  13. Overview of NASA Electrified Aircraft Propulsion Research for Large Subsonic Transports

    Science.gov (United States)

    Jansen, Ralph H.; Bowman, Cheryl; Jankovsky, Amy; Dyson, Rodger; Felder, James

    2017-01-01

    NASA is investing in Electrified Aircraft Propulsion (EAP) research as part of the portfolio to improve the fuel efficiency, emissions, and noise levels in commercial transport aircraft. Turboelectric, partially turboelectric, and hybrid electric propulsion systems are the primary EAP configurations being evaluated for regional jet and larger aircraft. The goal is to show that one or more viable EAP concepts exist for narrow body aircraft and mature tall-pole technologies related to those concepts. A summary of the aircraft system studies, technology development, and facility development is provided. The leading concept for mid-term (2035) introduction of EAP for a single aisle aircraft is a tube and wing, partially turbo electric configuration (STARC-ABL), however other viable configurations exist. Investments are being made to raise the TRL level of light weight, high efficiency motors, generators, and electrical power distribution systems as well as to define the optimal turbine and boundary layer ingestion systems for a mid-term tube and wing configuration. An electric aircraft power system test facility (NEAT) is under construction at NASA Glenn and an electric aircraft control system test facility (HEIST) is under construction at NASA Armstrong. The correct building blocks are in place to have a viable, large plane EAP configuration tested by 2025 leading to entry into service in 2035 if the community chooses to pursue that goal.

  14. Extracellular mass transport considerations for space flight research concerning suspended and adherent in vitro cell cultures

    Science.gov (United States)

    Klaus, David M.; Benoit, Michael R.; Nelson, Emily S.; Hammond, Timmothy G.

    2004-01-01

    Conducting biological research in space requires consideration be given to isolating appropriate control parameters. For in vitro cell cultures, numerous environmental factors can adversely affect data interpretation. A biological response attributed to microgravity can, in theory, be explicitly correlated to a specific lack of weight or gravity-driven motion occurring to, within or around a cell. Weight can be broken down to include the formation of hydrostatic gradients, structural load (stress) or physical deformation (strain). Gravitationally induced motion within or near individual cells in a fluid includes sedimentation (or buoyancy) of the cell and associated shear forces, displacement of cytoskeleton or organelles, and factors associated with intra- or extracellular mass transport. Finally, and of particular importance for cell culture experiments, the collective effects of gravity must be considered for the overall system consisting of the cells, their environment and the device in which they are contained. This does not, however, rule out other confounding variables such as launch acceleration, on orbit vibration, transient acceleration impulses or radiation, which can be isolated using onboard centrifuges or vibration isolation techniques. A framework is offered for characterizing specific cause-and-effect relationships for gravity-dependent responses as a function of the above parameters.

  15. Universal quantifier derived from AFM analysis links cellular mechanical properties and cell-surface integration forces with microbial deposition and transport behavior.

    Science.gov (United States)

    Li, Yueyun; Wang, Xin; Onnis-Hayden, Annalisa; Wan, Kai-tak; Gu, April Z

    2014-01-01

    In this study, we employed AFM analysis combined with mathematical modeling for quantifying cell-surface contact mechanics and magnitude and range of cell-surface interaction forces for seven bacterial strains with a wide range of cell morphology, dimension, and surface characteristics. Comprehensive cell-surface characterization including surface charge, extracellular polymeric substance content, hydrophobicity, and cell-cell aggregation analyses were performed. Flow-through column tests were employed to determine the attachment efficiency and deposition-transport behavior of these bacterial strains. No statistically significant correlation between attachment efficiency and any single-cell surface property was identified. Single-cell characterization by atomic force microscopy (AFM) yielded the mechanical deformation and elastic modulus, penetration resistance to AFM probe penetration by cellular surface substances (CSS), range and magnitude of the repulsive-attractive intersurface forces, and geometry of each strain. We proposed and derived a universal dimensionless modified Tabor's parameter to integrate all these properties that account for their collective behavior. Results showed that the Tabor parameter derived from AFM analysis correlated well with experimentally determined attachment efficiency (α), which therefore is able to link microscale cell-surface properties with macroscale bacterial transport behavior. Results suggested that the AFM tests performed between a single cell and a surface captured the key quantities of the interactions between the cell and the surface that dictate overall cell attachment behavior. Tabor's parameter therefore can be potentially incorporated into the microbial transport model.

  16. 鱼类保活运输的研究进展%Advances research of transportation to keep fish alive

    Institute of Scientific and Technical Information of China (English)

    刘骁; 谢晶; 黄硕琳

    2015-01-01

    文中对目前国内外常用的净水法、增氧法、降温法和麻醉法等鱼类保活运输方法进行了综述,介绍了鱼体体质、暂养、水质和外力胁迫等因素对鱼类保活运输质量的影响,从行为和生理方面阐述了运输过程鱼类产生的应激反应及其相应的研究方法.文章最后分析了鱼类保活运输存在的问题,并对其发展前景进行了展望.%Recently,with constantly grew of live fish market,more and more attention had been paid on the research of keeping fish alive transportation.Current fish transportation techniques such as water purification,aerobic,drop temperature and anesthesia were reviewed.The main factors which influenced transportation,such as aquatic species,water quality,temperature,and forcing stress were introduced in the paper.The stress response and relevant research methods in the process of fish transportation through behavioral and physiological aspect were expounded.Finally,existing problems of the transportation were analyzed in order to put forward research direction.The purpose of this paper was to provide reference for research and improvement in transport alive fish.

  17. Analysis of different research activities and description of parties within the Swedish Knowledge Centre for Renewable Transportation Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lundgren, Joakim [Bio4Energy, Luleaa (Sweden); Wallberg, Ola [Lund Univ., Lund (Sweden)

    2012-07-01

    The Swedish Knowledge Centre for Renewable Transportation Fuels (f3) is a nationwide centre, which through cooperation and a systems approach will contribute to the development of sustainable fossil free fuels for transportation. The centre will, through joint efforts by the centre partners, perform syntheses of current research about the production of renewable fuels as well as supplementing research, such as comparative systems analyses of fuels, processes, raw materials and plant design. f3 provides a platform for collaboration between centre partners, with a common vision of sustainable fuels for transportation and common objectives. The centre partners include Sweden's most active universities and research institutes within the field, as well as a number of highly relevant industrial companies. New fuels will be an important component of a strategy to reduce both greenhouse gas emissions and our dependence on petroleum. The Swedish Government has established a vision for the Swedish transport industry to function without fossil fuels by 2030. Such a development requires a concerted response, with participation from all stake holders. Swedish researchers in various disciplines and at various colleges and institutes have a unique breadth and they are at the forefront in several areas of knowledge appropriate for a centre for renewable fuels. Through collaboration, f3 should help to link engineering and systems research and communicate results and conclusions from these research efforts. Within the f3 centre, several parties with different research activities are represented. This document is a snapshot of the different parties at the end of 2011 where the stake holders are described and their current research is highlighted. Also, the different projects conducted by the parties have been categorized and presented at the end of the document.

  18. Description of the primary flight display and flight guidance system logic in the NASA B-737 transport systems research vehicle

    Science.gov (United States)

    Knox, Charles E.

    1990-01-01

    A primary flight display format was integrated with the flight guidance and control system logic in support of various flight tests conducted with the NASA Transport Systems Research Vehicle B-737-100 airplane. The functional operation of the flight guidance mode control panel and the corresponding primary flight display formats are presented.

  19. Self-assembly, redox activity, and charge transport of functional surface nano-architectures by molecular design

    Science.gov (United States)

    Skomski, Daniel

    inter-layer charge transport allowed electronic property characterization with the scanning tunneling microscope, demonstrating a narrowing of the film bandgap with increasing thickness which evidenced electron conjugation in the film. These results have advanced our understanding of supramolecular self-assembly at surfaces and how it can impact future technologies from organic-based materials.

  20. Minding the gap: Thinking through spatiotemporal scaling challenges in Earth surface dynamics research

    Science.gov (United States)

    Viles, Heather

    2017-04-01

    Research into the dynamics of Earth's surface is diverse, interdisciplinary and challenging, but also an important geoscience contribution to understanding human-landscape interactions in the Anthropocene. Scale issues often thwart our ability to provide answers to important questions of how the Earth's surface has changed in the past and may change in the future. This paper reflects on four major common components of Earth surface dynamics research projects (i.e. how to identify and frame a research question, how to design a study to answer that question, difficulties with data, how to use data to answer the question) and identifies the most important spatiotemporal scale challenges. A case study of an experimental study of rock breakdown in arid environments is used to illustrate these challenges, and to demonstrate the importance of clear conceptualisation and critical thinking in overcoming them.

  1. Chamber transport

    Energy Technology Data Exchange (ETDEWEB)

    OLSON,CRAIG L.

    2000-05-17

    Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system.

  2. 77 FR 38709 - Surface Transportation Environment and Planning Cooperative Research Program (STEP)

    Science.gov (United States)

    2012-06-28

    .... FOR FURTHER INFORMATION CONTACT: Gabe Rousseau, Acting Director, Office of Human Environment, (202) 366-8044, Gabe.Rousseau@dot.gov or Seetha Srinivasan, Office of the Chief Counsel, (202) 366-4099...

  3. The Human Dopamine Transporter: Investigating the Role of the C Terminus in Surface Targeting

    DEFF Research Database (Denmark)

    Vægter, Christian Bjerggaard

    2005-01-01

    Dopaminergic neurotransmission is involved in the modulation of locomotor activity, emotional behavior, memory and cognition. Hence, imbalances in the dopaminergic system in humans have been hypothesized to contribute to the pathogenesis of a number of illnesses, including Parkinson's disease...... also found evidence for a direct interaction between DAT and the Ca2+/calmodulin dependent kinase II α (CaMKIIα) and this interaction seems to depend on the same epitopes that are essential for surface targeting of DAT. Finally, using a fluorescently labelled cocaine analogue we were able to detect...

  4. Transport Properties of Hydrogen-Terminated Silicon Surface Controlled by Ionic-Liquid Gating

    Science.gov (United States)

    Sasama, Yosuke; Yamaguchi, Takahide; Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko

    2017-01-01

    We fabricated electric double-layer transistors on the hydrogen-terminated (111)-oriented surface of non-doped silicon using ionic liquid as a gate dielectric. We introduced hole carriers into silicon with the application of a negative gate voltage. The sheet resistance of silicon was controlled by more than three orders of magnitude at 220 K by changing the gate voltage. The temperature dependence of sheet resistance became weak as the gate voltage was increased, suggesting the approach to an insulator-metal transition.

  5. Spectroscopic measurements of the surface waters for evaluating the fresh-water transport to marine environments in the Southern Baltic

    Science.gov (United States)

    Drozdowska, Violetta; Markuszewski, Piotr; Kowalczyk, Jakub; Makuch, Przemysław; Pakszyc, Paulina; Strzałkowska, Agata; Piskozub, Jacek; Petelski, Tomasz; Zieliński, Tymon; Gutowska, Dorota

    2014-05-01

    To asses concentration and spatial distribution of surface-active molecules (surfactants) the spectrophotometric and spectrofluorometric measurements of water samples taken from a surface film and a depth 0.5 m were carried out during three cruises of r/v Oceania in Springs' 2010-2011 and Autumn' 2012. Measurements were conducted along the transects from the river outlets to the open waters of the Southern Baltic Sea. Surfactants consist of polar molecules of marine dissolved organic matter and are chemically not entirely classified. However, fractions of dissolved organic matter having chromophores or fluorophores (CDOM or FDOM) are recognized through their specific absorption and fluorescence spectra. The sea surface is a layer of transition between the atmosphere and the sea, where there is a variety of biological, physical and chemical processes which contribute to the accumulation and exchange of surfactants, the chemical species concentrated in the surface layer (surface active agents). The main source of marine surfactants are remains of phytoplankton and its degradation products, created by bacterial activity, and as a result of condensation of molecules of low molecular weight to form of surface-active macromolecules. The presence of surfactants in the surface layers can significantly affect the access of solar energy into the sea as well as the air-sea interaction processes. The main objective of the research was to investigate the luminescent properties of surfactants, sampled in different regions of the Southern Baltic, and to find the differences between a surface film and a subsurface layer (of 50 cm). The next aim was to combine the differences in optical properties with the different dynamics for various river outlets. The results of spectrophotometric studies show the differences in the intensity of spectral bands, particularly between coastal (estuaries) and the open sea zones. Also, analysis of the spectra shows differences between areas of the

  6. Assimilation of surface NO2 and O3 observations into the SILAM chemistry transport model

    Science.gov (United States)

    Vira, J.; Sofiev, M.

    2015-02-01

    This paper describes the assimilation of trace gas observations into the chemistry transport model SILAM (System for Integrated modeLling of Atmospheric coMposition) using the 3D-Var method. Assimilation results for the year 2012 are presented for the prominent photochemical pollutants ozone (O3) and nitrogen dioxide (NO2). Both species are covered by the AirBase observation database, which provides the observational data set used in this study. Attention was paid to the background and observation error covariance matrices, which were obtained primarily by the iterative application of a posteriori diagnostics. The diagnostics were computed separately for 2 months representing summer and winter conditions, and further disaggregated by time of day. This enabled the derivation of background and observation error covariance definitions, which included both seasonal and diurnal variation. The consistency of the obtained covariance matrices was verified using χ2 diagnostics. The analysis scores were computed for a control set of observation stations withheld from assimilation. Compared to a free-running model simulation, the correlation coefficient for daily maximum values was improved from 0.8 to 0.9 for O3 and from 0.53 to 0.63 for NO2.

  7. Predicting the Amplitude and Hemispheric Asymmetry of Solar Cycle 25 with Surface Flux Transport

    CERN Document Server

    Hathaway, David H

    2016-01-01

    Evidence strongly indicates that the strength of the Sun's polar fields near the time of a sunspot cycle minimum determines the strength of the following solar activity cycle. We use our Advective Flux Transport (AFT) code, with flows well constrained by observations, to simulate the evolution of the Sun's polar magnetic fields from early 2016 to the end of 2019 --- near the expected time of Cycle 24/25 minimum. We run a series of simulations in which the uncertain conditions (convective motion details, active region tilt, and meridional flow profile) are varied within expected ranges. We find that the average strength of the polar fields near the end of Cycle 24 will be similar to that measured near the end of Cycle 23, indicating that Cycle 25 will be similar in strength to the current cycle. In all cases the polar fields are asymmetric with fields in the south stronger than those in the north. This asymmetry would be more pronounced if not for the predicted weakening of the southern polar fields in late 20...

  8. Human papillomavirus type 16 entry: retrograde cell surface transport along actin-rich protrusions.

    Directory of Open Access Journals (Sweden)

    Mario Schelhaas

    Full Text Available The lateral mobility of individual, incoming human papillomavirus type 16 pseudoviruses (PsV bound to live HeLa cells was studied by single particle tracking using fluorescence video microscopy. The trajectories were computationally analyzed in terms of diffusion rate and mode of motion as described by the moment scaling spectrum. Four distinct modes of mobility were seen: confined movement in small zones (30-60 nm in diameter, confined movement with a slow drift, fast random motion with transient confinement, and linear, directed movement for long distances. The directed movement was most prominent on actin-rich cell protrusions such as filopodia or retraction fibres, where the rate was similar to that measured for actin retrograde flow. It was, moreover, sensitive to perturbants of actin retrograde flow such as cytochalasin D, jasplakinolide, and blebbistatin. We found that transport along actin protrusions significantly enhanced HPV-16 infection in sparse tissue culture, cells suggesting a role for in vivo infection of basal keratinocytes during wound healing.

  9. Transport-transformation of Polycyclic Aromatic Hydrocarbons in Surface Waters%地表水中多环芳烃迁移转化研究进展

    Institute of Scientific and Technical Information of China (English)

    许晓伟; 黄岁樑

    2011-01-01

    多环芳烃类(Polycyclic Aromatic Hydrocarbons,PAHs)物质是广泛存在于环境中的一类持久性有机污染物,具有难降解、易富集和"三致"的特点,可能严重危害人类健康和生态环境.文章主要阐述PAHs在环境中的污染,重点是对地表水环境的污染;总结PAHs在地表水环境中迁移转化研究的进展和成果,重点探讨了多环芳烃在水-颗粒物(沉积物)闯的吸附解吸研究进展,也对多环芳烃在气-水间的交换、光降解、植物吸收、微生物降解等迁移转化行为做了简单综述;认为今后的研究方向是对多环芳烃的吸附动力学模型及吸附影响因素的深入研究,及水中多环芳烃的植物及微生物修复降解研究.%Polycyclic aromatic hydrocarbons (PAHs) as common pollutants in the environment with characteristics of carcinogen, teratogen and mutagen, are quite harmful to human beings and the ecological environment. Contamination of PAHs in environment especially in surface waters was briefed. Transport-transformation of PAHs in surface waters including adsorption-desorption, exchange between water and atmosphere, photodegradation, uptake of plants and biodegradation were reviewed. It was proposed that more researches should be put on transport-transformation mechanism, remediation and degradation of PAHs by plants and microbe.

  10. Volatile transport on inhomogeneous surfaces: II. Numerical calculations (VT3D)

    Science.gov (United States)

    Young, Leslie A.

    2017-03-01

    Several distant icy worlds have atmospheres that are in vapor-pressure equilibrium with their surface volatiles, including Pluto, Triton, and, probably, several large KBOs near perihelion. Studies of the volatile and thermal evolution of these have been limited by computational speed, especially for models that treat surfaces that vary with both latitude and longitude. In order to expedite such work, I present a new numerical model for the seasonal behavior of Pluto and Triton which (i) uses initial conditions that improve convergence, (ii) uses an expedient method for handling the transition between global and non-global atmospheres, (iii) includes local conservation of energy and global conservation of mass to partition energy between heating, conduction, and sublimation or condensation, (iv) uses time-stepping algorithms that ensure stability while allowing larger timesteps, and (v) can include longitudinal variability. This model, called VT3D, has been used in Young (2012a, 2012b), Young (2013), Olkin et al. (2015), Young and McKinnon (2013), and French et al. (2015). Many elements of VT3D can be used independently. For example, VT3D can also be used to speed up thermophysical models (Spencer et al., 1989) for bodies without volatiles. Code implementation is included in the supplemental materials and is available from the author.

  11. Horse Injury during Non-Commercial Transport: Findings from Researcher-Assisted Intercept Surveys at Southeastern Australian Equestrian Events

    Directory of Open Access Journals (Sweden)

    Christopher B. Riley

    2016-10-01

    Full Text Available Equine transportation research has largely focused on the commercial land movement of horses. Data on the incidence and factors associated with horse injuries during non-commercial transportation (privately owned horse trucks and trailers is scant. This study surveyed 223 drivers transporting horses to 12 equestrian events in southeastern Australia. Data collected encompassed driver demographics, travel practice, vehicle characteristics, and incidents involving horse injury. Approximately 25% (55/223 of participants reported that their horses were injured during transportation. Of these 72% were owner classified as horse associated (scrambling, slipping and horse-horse interaction, 11% due to mechanical failure, and 6% due to driver error. Horse injury was not significantly associated with driver age, gender, or experience. Participants that answer the telephone whilst driving were more likely to have previously had a horse injured ( p = 0.04. There was a trend for participants with <8 hours sleep prior to the survey to have experienced a previous transportation-related injury ( p = 0.056. Increased trailer age was associated with a greater number of injury reports (r² = 0.20; p < 0.04. The diversity in trailer models prevented identification of the importance of individual design features. This study highlights the potential for horses to sustain transportation injuries in privately owned vehicles and warrants further study to address this risk to their welfare.

  12. Transport system

    NARCIS (Netherlands)

    Drenth, K.F.

    1999-01-01

    The transport system comprises at least one road surface (2) and at least one vehicle (4) on wheels (6). The road surface (2) has a substantially bowl-shaped cross section and the vehicle (4) is designed so that the wheels (6) run directly on the road surface (2) while the road surface (2) acts as a

  13. Research on Development Measures of Low-carbon Transportation in Beijing

    Directory of Open Access Journals (Sweden)

    Gang Zong

    2014-05-01

    Full Text Available With the development of economy, vehicle ownership is growing rapidly. People gradually concentrate on the energy consumption of transportation industry and environmental pollution. Because of air pollution, energy consumption, climate change and other problems, people in major cities pay more attention to energy conservation and emission reduction in transportation. Transportation industry is an important source of energy consumption and carbon emission. Facing the task of energy conservation and emission reduction in the Twelfth Five-year Plan for economic and social development, it is extremely urgent to adjust the transportation industry and take road of low-carbon transportation. Low-carbon transportation is an important breakthrough for Beijing to readjust industrial structure and transform the economic development pattern; it is also a demand for Culture-enriched Beijing, Technology-empowered Beijing, Environment-friendly Beijing as well as an inevitable choice for the coordinated development of economy, society and environment. This paper analyzes the status quo and major problems facing Beijing low-carbon transportation and comes up with policy advice for low-carbon transportation development.

  14. Transport operations in container terminals : Literature overview, trends, research directions and classification scheme

    NARCIS (Netherlands)

    Carlo, Hector J.; Vis, Iris F. A.; Roodbergen, Kees Jan

    2014-01-01

    Internal transport operations connect the seaside, yard side, and landside processes at container terminals. This paper presents an in-depth overview of transport operations and the material handling equipment used, highlights current industry trends and developments, and proposes a new classificati

  15. Botswana water and surface energy balance research program. Part 1: Integrated approach and field campaign results

    Science.gov (United States)

    Vandegriend, A. A.; Owe, M.; Vugts, H. F.; Ramothwa, G. K.

    1992-01-01

    The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. Results of the first part of the program (Botswana 1) which ran from 1 Jan. 1988 - 31 Dec. 1990 are summarized. Botswana 1 consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components in general are described and activities performed during the surface energy modeling component including the extensive field campaign are summarized. The results of the passive microwave component are summarized. The key of the field campaign was a multilevel approach, whereby measurements by various similar sensors were made at several altitudes and resolution. Data collection was performed at two adjacent sites of contrasting surface character. The following measurements were made: micrometeorological measurements, surface temperatures, soil temperatures, soil moisture, vegetation (leaf area index and biomass), satellite data, aircraft data, atmospheric soundings, stomatal resistance, and surface emissivity.

  16. Hacking Your Ride: Is Web 2.0 Creating Vulnerabilities To Surface Transportation

    Science.gov (United States)

    2016-09-01

    during the 2010– 2011 floods in Australia.53 They were able to identify influential Twitter users during the floods and the users’ methods for...intervals, thus creating traffic congestion and promoting alternate routes .159 In the research cited, methods two through four caused Waze to display...traffic congestion. Waze will suggest alternate travel routes should the targeted route have a comparably longer travel time.160 Method one, in and of

  17. What is greener than a VMT tax? The case for an indexed energy user fee to finance us surface transportation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, David L [ORNL

    2011-01-01

    Highway finance in the United States is perceived by many to be in a state of crisis, primarily due to the erosion of motor fuel tax revenues due to inflation, fuel economy improvement, increased use of alternative sources of energy and diversion of revenues to other purposes. Monitoring vehicle miles of travel (VMT) and charging highway users per mile has been proposed as a replacement for the motor fuel tax. A VMT user fee, however, does not encourage energy efficiency in vehicle design, purchase and operation, as would a user fee levied on all forms of commercial energy used for transportation and indexed to the average efficiency of vehicles on the road and to inflation. An indexed roadway user toll on energy (IRoUTE) would induce two to four times as much reduction in greenhouse gas (GHG) emissions and petroleum use as a pure VMT user fee. However, it is not a substitute for pricing GHG emissions and would make only a small but useful contribution to reducing petroleum dependence. An indexed energy user fee cannot adequately address the problems of traffic congestion and heavy vehicle cost responsibility. It could, however, be a key component of a comprehensive system of financing surface transportation that would eventually also include time and place specific monitoring of VMT for congestion pricing, externality charges and heavy vehicle user fees.

  18. Moving beyond the limits of mass transport in liquid absorbent microfilms through the implementation of surface-induced vortices

    Energy Technology Data Exchange (ETDEWEB)

    Bigham, S; Yu, DZ; Chugh, D; Moghaddam, S

    2014-02-01

    The slow diffusion of an absorbate molecule into an absorbent often makes the absorption process a rate-limiting step in many applications. In cases involving an absorbate with a high heat of phase change, such as water absorption into a LiBr (lithium bromide) solution, the absorption rate is further slowed due to significant heating of the absorbent. Recently, it has been demonstrated that constraining a LiBr solution film by a hydrophobic porous structure enables manipulation of the solution flow thermohydraulic characteristics. Here, it is shown that mass transport mode in a constrained laminar solution flow can be changed from diffusive to advective. This change in mode is accomplished through stretching and folding the laminar streamlines within the solution film via the implementation of micro-scale features on the flow channel surface. The process induces vortices within the solution film, which continuously bring concentrated solution from the bottom and middle of the solution channel to its interface with the vapor phase, thus leading to a significant enhancement in the absorption rate. The detailed physics of the involved transport processes is elucidated using the LBM (Lattice Boltzmann Method). Published by Elsevier Ltd.

  19. Implication of surface modified NZVI particle retention in the porous media: Assessment with the help of 1-D transport model

    Indian Academy of Sciences (India)

    Trishikhi Raychoudhury; Vikranth Kumar Surasani

    2017-06-01

    Retention of surface-modified nanoscale zero-valent iron (NZVI) particles in the porous media near the point of injection has been reported in the recent studies. Retention of excess particles in porous media can alter the media properties. The main objectives of this study are, therefore, to evaluate the effect of particle retention on the porous media properties and its implication on further NZVI particle transport under different flow conditions. To achieve the objectives, a one-dimensional transport model is developed by considering particle deposition, detachment, and straining mechanisms along with the effect of changes in porosity resulting from retention of NZVI particles. Two different flow conditions are considered for simulations. The first is a constant Darcy’s flow rate condition, which assumes a change in porosity, causes a change in pore water velocity and the second, is a constant head condition, which assumes the change in porosity, influence the permeability and hydraulic conductivity (thus Darcy’s flow rate). Overall a rapid decrease in porosity was observed as a result of high particle retention near the injection points resulting in a spatial distribution of deposition rate coefficient. In the case of constant head condition, the spatial distribution of Darcy’s velocities is predicted due to variation in porosity and hydraulic conductivity. The simulation results are compared with the data reported from the field studies; which suggests straining is likely to happen in the real field condition.

  20. Photodetection and transport properties of surface capped silicon nanowires arrays with polyacrylic acid

    Directory of Open Access Journals (Sweden)

    Kamran Rasool

    2013-08-01

    Full Text Available Efficient hybrid photodetector consisting of silicon nanowires (SiNWs (∼40 μm capped with Polyacrylic Acid (PAA is demonstrated. Highly diluted PAA with deionized (DI water was spun directly on vertical SiNW arrays prepared by metal assisted electroless chemical etching (MACE technique. We have observed ∼9, 4 and 9 times enhancement in responsivity, detectivity and external quantum efficiency in SiNWs/PAA hybrid device in comparison to SiNWs only device. Higher electrical current and photodetection may be due to the increment of hydrophilic content (acceptor like states on SiNWs interface. The higher photosensitivity can also be attributed to the presence of low refractive index PAA around SiNWs which causes funneling of photon energy into SiNWs. Surface roughness of SiNWs leads to immobilization of charge carriers and hence shows persistent photoconductivity.

  1. Optically tunable spin transport on the surface of a topological insulator

    Science.gov (United States)

    Yudin, D.; Kibis, O. V.; Shelykh, I. A.

    2016-10-01

    The emerging field of spinoptronics has a potential to supersede the functionality of modern electronics, while a proper description of strong light-matter coupling pose the most intriguing questions from both fundamental scientific and technological perspectives. In this paper we address a highly relevant issue for such a development. We theoretically explore spin dynamics on the surface of a 3D topological insulator (TI) irradiated with an off-resonant high-frequency electromagnetic wave. The strong coupling between electrons and the electromagnetic wave drastically modifies the spin properties of TI. The effects of irradiation are shown to result in anisotropy of electron energy spectrum near the Dirac point and suppression of spin current and are investigated in detail in this work.

  2. Thermoelectric transport in surface- and antimony-doped bismuth telluride nanoplates

    Science.gov (United States)

    Pettes, Michael Thompson; Kim, Jaehyun; Wu, Wei; Bustillo, Karen C.; Shi, Li

    2016-10-01

    We report the in-plane thermoelectric properties of suspended (Bi1-xSbx)2Te3 nanoplates with x ranging from 0.07 to 0.95 and thicknesses ranging from 9 to 42 nm. The results presented here reveal a trend of increasing p-type behavior with increasing antimony concentration, and a maximum Seebeck coefficient and thermoelectric figure of merit at x ˜ 0.5. We additionally tuned extrinsic doping of the surface using a tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) coating. The lattice thermal conductivity is found to be below that for undoped ultrathin Bi2Te3 nanoplates of comparable thickness and in the range of 0.2-0.7 W m-1 K-1 at room temperature.

  3. The imprint of surface fluxes and transport on variations in total column carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Keppel-Aleks, G [California Institute of Technology, Pasadena; Wennberg, PO [California Institute of Technology, Pasadena; Washenfelder, RA [National Oceanic and Atmospheric Admin; Wunch, D [California Institute of Technology, Pasadena; Schneider, T [California Institute of Technology, Pasadena; Toon, GC [Jet Propulsion Laboratory, Pasadena, CA; Andres, Robert Joseph [ORNL; Blavier, J-F [Jet Propulsion Laboratory, Pasadena, CA; Connor, B [BC Consulting; Davis, K. J. [Pennsylvania State University; Desai, Desai Ankur R. [University of Wisconsin, Madison; Messerschmidt, J [University of Bremen, Bremen, Germany; Notholt, J [University of Bremen, Bremen, Germany; Roehl, CM [California Institute of Technology, Pasadena; Sherlock, V [National Institue of Water and Atmospheric Research, New Zealand; Stephens, BB [National Center for Atmospheric Research (NCAR); Vay, SA [NASA Langley Research Center; Wofsy, Steve [Harvard University

    2012-01-01

    New observations of the vertically integrated CO{sub 2} mixing ratio, , from ground-based remote sensing show that variations in are primarily determined by large-scale flux patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local fluxes. Observations of both and CO{sub 2} concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface fluxes on atmospheric CO{sub 2}, these synoptic-scale variations provide useful information that can be used to reveal the meridional flux distribution. We estimate the meridional gradient in from covariations in and potential temperature, {theta}, a dynamical tracer, on synoptic timescales to evaluate surface flux estimates commonly used in carbon cycle models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric fluxes underestimate both the seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal fluxes better fit the observations. Our simulations suggest that climatological mean CASA fluxes underestimate boreal growing season NEE (between 45-65{sup o} N) by {approx}40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.

  4. Role of rainfall intensity and hydrology in nutrient transport via surface runoff.

    Science.gov (United States)

    Kleinman, Peter J A; Srinivasan, M S; Dell, Curtis J; Schmidt, John P; Sharpley, Andrew N; Bryant, Ray B

    2006-01-01

    Loss of soil nutrients in runoff accelerates eutrophication of surface waters. This study evaluated P and N in surface runoff in relation to rainfall intensity and hydrology for two soils along a single hillslope. Experiments were initiated on 1- by 2-m plots at foot-slope (6%) and mid-slope (30%) positions within an alfalfa (Medicago sativa L.)-orchardgrass (Dactylis glomerata L.) field. Rain simulations (2.9 and 7.0 cm h(-1)) were conducted under wet (spring) and dry (late-summer) conditions. Elevated, antecedent soil moisture at the foot-slope during the spring resulted in less rain required to generate runoff and greater runoff volumes, compared with runoff from the well-drained mid-slope in spring and at both landscape positions in late summer. Phosphorus in runoff was primarily in dissolved reactive form (DRP averaged 71% of total P), with DRP concentrations from the two soils corresponding with soil test P levels. Nitrogen in runoff was mainly nitrate (NO3-N averaged 77% of total N). Site hydrology, not chemistry, was primarily responsible for variations in mass N and P losses with landscape position. Larger runoff volumes from the foot-slope produced higher losses of total P (0.08 kg ha(-1)) and N (1.35 kg ha(-1)) than did runoff from the mid-slope (0.05 total P kg ha(-1); 0.48 kg N ha(-1)), particularly under wet, spring-time conditions. Nutrient losses were significantly greater under the high intensity rainfall due to larger runoff volumes. Results affirm the critical source area concept for both N and P: both nutrient availability and hydrology in combination control nutrient loss.

  5. Impact of surface coating and environmental conditions on the fate and transport of silver nanoparticles in the aquatic environment.

    Science.gov (United States)

    Ellis, Laura-Jayne A; Valsami-Jones, Eugenia; Lead, Jamie R; Baalousha, Mohammed

    2016-10-15

    The role of surface coating (polyvinylpyrrolidone (PVP) and citrate) and water chemistry on the fate and behavior of AgNPs in aquatic microcosms is reported in this study. The migration and transformation of the AgNPs was examined in low (ultrapure water-UPW) and high ionic strength (moderately hard water - MHW) preparations, and in the presence of modeled natural organic matter (NOM) of Suwannee River Fulvic Acid (SRFA). The migration and fate of the AgNPs in the microcosms was validated using a sedimentation-diffusion model and the aggregation behavior was monitored by UV-visible spectrometry (UV-vis). Dissolved and particulate Ag concentrations (% Ag) were analyzed by ultrafiltration methods. Imaging of the AgNPs was captured using transmission electron microscopy (TEM). Results indicate that PVP-coated AgNPs (PVP-AgNPs) remained stable for 28days with similarly distributed concentrations of the PVP-AgNPs throughout the columns in each of the water conditions after approximately 96h (4days). The sedimentation-diffusion model confirmed PVP-AgNP stability in each condition, by showing diffusion dominated transport by using the original unaltered AgNP sizes to fit the parameters. In comparison, citrate AgNPs were largely unstable in the more complex water preparations (MHW). In MHW, aggregation dominated behavior followed by sedimentation/dissolution controlled transport was observed. The addition of SRFA to MHW resulted in small stabilizing effects, to the citrate coated AgNPs, producing smaller sized AgNPs (TEM) and mixed sedimentation and diffusion migration compared the studies absent of SRFA. The results suggest that surface coating and solution chemistry has a major impact on AgNP stability, furthermore the corresponding modeling will support the experimental understanding of the overall fate of AgNPs in the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Unraveling the Role of Transport, Electrocatalysis, and Surface Science in the Solid Oxide Fuel Cell Cathode Oxygen Reduction Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gopalan, Srikanth [Boston Univ., MA (United States)

    2017-04-06

    This final report for project FE0009656 covers the period from 10/01/2012 to 09/30/2015 and covers research accomplishments on the effects of carbon dioxide on the surface composition and structure of cathode materials for solid oxide fuel cells (SOFCs), specifically La1-xSrxFeyCo1- yO3-δ (LSCF). Epitaxially deposited thin films of LSCF on various single-crystal substrates have revealed the selective segregation of strontium to the surface thereby resulting in a surface enrichment of strontium. The near surface compositional profile in the films have been measured using total x-ray fluorescence (TXRF), and show that the kinetics of strontium segregation are higher at higher partial pressures of carbon dioxide. Once the strontium segregates to the surface, it leads to the formation of precipitates of SrO which convert to SrCO3 in the presence of even modest concentrations of carbon dioxide in the atmosphere. This has important implications for the performance of SOFCs which is discussed in this report. These experimental observations have also been verified by Density Functional Theory calculations (DFT) which predict the conditions under which SrO and SrCO3 can occur in LSCF. Furthermore, a few cathode compositions which have received attention in the literature as alternatives to LSCF cathodes have been studied in this work and shown to be thermodynamically unstable under the operating conditions of the SOFCs.

  7. Mechanisms controlling surface ozone over East Asia: a multiscale study coupling regional and global chemical transport models

    Science.gov (United States)

    Lin, M.; Holloway, T.; Oki, T.; Streets, D. G.; Richter, A.

    2008-12-01

    Mechanisms controlling surface ozone (O3) over East Asia are examined using the regional Community Multiscale Air Quality (CMAQ) model at two horizontal scales: 81 km and 27 km. Through sensitivity studies and comparison with recently available satellite data and surface measurements in China and Japan, we find that the O3 budget over East Asia shows complex interactions among photochemical production, regional transport, meteorological conditions, burning of agricultural residues, and global inflows. For example, wintertime surface O3 over northern domain is sensitive to boundary conditions derived from the MOZART (Model for Ozone and Related Tracers) global model, whereas summertime O3 budget is controlled by the competitive processes between photochemical production and monsoonal intrusion of low-O3 marine air masses from tropical Pacific. We find that simulated surface O3 for 2001 does not exhibit the same sharp drop in July and August concentrations that is observed at two mountaintop sites (Tai and Hua) for 2004 and Beijing for 1995-2005. CMAQ sensitivity tests with two widely used photochemical schemes demonstrate that over the industrial areas in East Asia north of 30° N, SAPRC99 produces higher values of mean summertime O3 than CBIV, amounting to a difference of 10 ppb. In addition, analysis of NCEP winds and geopotential heights suggests that southwesterly monsoonal intrusion in central east China is weakened in August 2001 as compared with the climatologically mean for 1980-2005. Further examination of the O3 diurnal cycle at nine Japanese sites shows that boundary layer evolution has an important effect on the vertical mixing of ground-level O3, and error in near surface meteorology might contribute to overprediction of nighttime O3 in urban and rural areas. In conclusion, the uncertainties in simulating cloud activities and convection mixing, Asian monsoon circulation, photochemical production, and nighttime cooling explain why CMAQ with 81 km

  8. Mechanisms controlling surface ozone over East Asia: a multiscale study coupling regional and global chemical transport models

    Directory of Open Access Journals (Sweden)

    M. Lin

    2008-12-01

    Full Text Available Mechanisms controlling surface ozone (O3 over East Asia are examined using the regional Community Multiscale Air Quality (CMAQ model at two horizontal scales: 81 km and 27 km. Through sensitivity studies and comparison with recently available satellite data and surface measurements in China and Japan, we find that the O3 budget over East Asia shows complex interactions among photochemical production, regional transport, meteorological conditions, burning of agricultural residues, and global inflows. For example, wintertime surface O3 over northern domain is sensitive to boundary conditions derived from the MOZART (Model for Ozone and Related Tracers global model, whereas summertime O3 budget is controlled by the competitive processes between photochemical production and monsoonal intrusion of low-O3 marine air masses from tropical Pacific. We find that simulated surface O3 for 2001 does not exhibit the same sharp drop in July and August concentrations that is observed at two mountaintop sites (Tai and Hua for 2004 and Beijing for 1995–2005. CMAQ sensitivity tests with two widely used photochemical schemes demonstrate that over the industrial areas in East Asia north of 30° N, SAPRC99 produces higher values of mean summertime O3 than CBIV, amounting to a difference of 10 ppb. In addition, analysis of NCEP winds and geopotential heights suggests that southwesterly monsoonal intrusion in central east China is weakened in August 2001 as compared with the climatologically mean for 1980–2005. Further examination of the O3 diurnal cycle at nine Japanese sites shows that boundary layer evolution has an important effect on the vertical mixing of ground-level O3, and error in near surface meteorology might contribute to overprediction of nighttime O3 in urban and rural areas. In conclusion, the uncertainties in simulating cloud activities and

  9. Cell surface receptors for signal transduction and ligand transport - a design principles study

    Energy Technology Data Exchange (ETDEWEB)

    Shankaran, Harish; Resat, Haluk; Wiley, H. S.

    2007-06-01

    Although many different receptors undergo endocytosis, the system-level design principles that govern the evolution of receptor dynamics are far from fully understood. We have constructed a generalized mathematical model to understand how receptor internalization dynamics encodes receptor function and regulation. Parametric analysis of the response of receptor systems to ligand inputs reveals that receptors can be categorized a being: i) avidity-controlled where the response control depends primarily on the extracelluar ligand capture efficiency, ii) consumption-controlled where the ability to internalize surface-bound ligand is the primary control parameter, and iii) dual-sensitivity where both the avidity and consumption parameters are important. We show that the transferrin and low-density lipoprotein receptors are avidity-controlled, the vitellogenin receptor is consumption-controlled and epidermal growth factor receptor is a dual-sensitivity receptor. Significantly, we show that ligand-induced endocytosis is a mechanism to anhance the accuracy of signaling receptors rather than serving to attenuate signaling. Our analysis reveals that the location of a receptor system in the avidity-consumption parameter space can be used to understand both its function and its regulations.

  10. Surface roughness and phonon transport in thin Si nanowires: an atomistic study

    Science.gov (United States)

    Carrete, Jesus; Gallego, Luis Javier; Varela, Luis Miguel; Mingo, Natalio

    2011-03-01

    Good thermal insulation is much harder to achieve than electrical insulation. Thus, the astonishingly low thermal conductivities recently reported on Si nanowires came as a surprise, since the displayed values were an order of magnitude lower than predicted by the diffuse boundary limit of Casimir's theory. Recent theoretical work has employed the Born approximation to predict a very much enhanced boundary scattering rate that would lead to a thermal conductivity well below the Casimir limit. We present a Green's function calculation that answers the question of whether the Casimir limit to the phonon mean free path can be overcome by roughness. Our results show that the mean free path (MFP) and the thermal conductivity of a nanowire are very close to the Casimir limit for shallow disorder, and can only be pushed below it using very deep surface roughness, well beyond previous estimates. We also explore the limits of the Born approximation in this context using vacancies and isotopic impurities as defects. This work was supported by the Spanish MICINN/FEDER (FIS2008-04894/FIS) and the Xunta de Galicia (INCITE09E2R206033ES). J.Carrete thanks the Spanish Ministry of Education for a FPU grant.

  11. Cell-surface signaling in Pseudomonas: stress responses, iron transport, and pathogenicity.

    Science.gov (United States)

    Llamas, María A; Imperi, Francesco; Visca, Paolo; Lamont, Iain L

    2014-07-01

    Membrane-spanning signaling pathways enable bacteria to alter gene expression in response to extracytoplasmic stimuli. Many such pathways are cell-surface signaling (CSS) systems, which are tripartite molecular devices that allow Gram-negative bacteria to transduce an extracellular stimulus into a coordinated transcriptional response. Typically, CSS systems are composed of the following: (1) an outer membrane receptor, which senses the extracellular stimulus; (2) a cytoplasmic membrane-spanning protein involved in signal transduction from the periplasm to the cytoplasm; and (3) an extracytoplasmic function (ECF) sigma factor that initiates expression of the stimulus-responsive gene(s). Members of genus Pseudomonas provide a paradigmatic example of how CSS systems contribute to the global control of gene expression. Most CSS systems enable self-regulated uptake of iron via endogenous (pyoverdine) or exogenous (xenosiderophores, heme, and citrate) carriers. Some are also implicated in virulence, biofilm formation, and cell-cell interactions. Incorporating insights from the well-characterized alginate regulatory circuitry, this review will illustrate common themes and variations at the level of structural and functional properties of Pseudomonas CSS systems. Control of the expression and activity of ECF sigma factors are central to gene regulation via CSS, and the variety of intrinsic and extrinsic factors influencing these processes will be discussed.

  12. Facile spray-coating process for the fabrication of tunable adhesive superhydrophobic surfaces with heterogeneous chemical compositions used for selective transportation of microdroplets with different volumes.

    Science.gov (United States)

    Li, Jian; Jing, Zhijiao; Zha, Fei; Yang, Yaoxia; Wang, Qingtao; Lei, Ziqiang

    2014-06-11

    In this paper, tunable adhesive superhydrophobic ZnO surfaces have been fabricated successfully by spraying ZnO nanoparticle (NP) suspensions onto desired substrates. We regulate the spray-coating process by changing the mass percentage of hydrophobic ZnO NPs (which were achieved by modifying hydrophilic ZnO NPs with stearic acid) in the hydrophobic/hydrophilic ZnO NP mixtures to control heterogeneous chemical composition of the ZnO surfaces. Thus, the water adhesion on the same superhydrophobic ZnO surface could be effectively tuned by controlling the surface chemical composition without altering the surface morphology. Compared with the conventional tunable adhesive superhydrophobic surfaces, on which there were only three different water sliding angle values: lower than 10°, 90° (the water droplet is firmly pinned on the surface at any tilted angles), and the value between the two ones, the water adhesion on the superhydrophobic ZnO surfaces has been tuned effectively, on which the sliding angle is controlled from 2 ± 1° to 9 ± 1°, 21 ± 2°, 39 ± 3°, and 90°. Accordingly, the adhesive force can be adjusted from extremely low (∼2.5 μN) to very high (∼111.6 μN). On the basis of the different adhesive forces of the tunable adhesive superhydrophobic surfaces, the selective transportation of microdroplets with different volumes was achieved, which has never been reported before. In addition, we demonstrated a proof of selective transportation of microdroplets with different volumes for application in the droplet-based microreactors via our tunable adhesive superhydrophobic surfaces for the quantitative detection of AgNO3 and NaOH. The results reported herein realize the selective transportation of microdroplets with different volumes and we believe that this method would potentially be used in many important applications, such as selective water droplet transportation, biomolecular quantitative detection and droplet-based biodetection.

  13. Modeling disinfection of plastic poultry transport cages inoculated with Salmonella enteritids by slightly acidic electrolyzed water using response surface methodology.

    Science.gov (United States)

    Zang, Y T; Li, B M; Bing, Sh; Cao, W

    2015-09-01

    In order to reduce the risk of enteric pathogens transmission in animal farms, the disinfection effectiveness of slightly acidic electrolyzed water (SAEW, pH 5.85 to 6.53) for inactivating Salmonella Enteritidis on the surface of plastic poultry transport cages was evaluated. The coupled effects of the tap water cleaning time (5 to 15 s), SAEW treatment time (20 to 40 s), and available chlorine concentrations (ACCs) of 30 to 70 mg/l on the reductions of S. Enteritidis on chick cages were investigated using a central composite design of the response surface methodology (RSM). The established RS model had a goodness of fit quantified by the parameter R2 (0.971), as well as a lack of fit test (P>0.05). The maximum reduction of 3.12 log10 CFU/cm2 for S. Enteritidis was obtained for the cage treated with tap water cleaning for 15 s followed by SAEW treatment for 40 s at an ACC of 50 mg/l. Results indicate that the established RS model has shown the potential of SAEW in disinfection of bacteria on cages. © 2015 Poultry Science Association Inc.

  14. Summary of the FY 2005 Batteries for Advanced Transportation Technologies (BATT) research program annual review

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2005-08-01

    This document presents a summary of the evaluation and comments provided by the review panel for the FY 2005 Department of Energy (DOE) Batteries for Advanced Transportation Technologies (BATT) program annual review.

  15. Fostering child-centred approaches to transport research, planning and policy development: a pilot methodology

    CSIR Research Space (South Africa)

    Mashiri, M

    2007-01-01

    Full Text Available the development of social networks, and influencing their health and educational achievements. Yet children and young people receive remarkably little attention in transport policy and planning. Since children constitute over half the population of most developing...

  16. Short communication: expression of transporters and metabolizing enzymes in the female lower genital tract: implications for microbicide research.

    Science.gov (United States)

    Zhou, Tian; Hu, Minlu; Cost, Marilyn; Poloyac, Samuel; Rohan, Lisa

    2013-11-01

    Topical vaginal microbicides have been considered a promising option for preventing the male-to-female sexual transmission of HIV; however, clinical trials to date have not clearly demonstrated robust and reproducible effectiveness results. While multiple approaches may help enhance product effectiveness observed in clinical trials, increasing the drug exposure in lower genital tract tissues is a compelling option, given the difficulty in achieving sufficient drug exposure and positive correlation between tissue exposure and microbicide efficacy. Since many microbicide drug candidates are substrates of transporters and/or metabolizing enzymes, there is emerging interest in improving microbicide exposure and efficacy through local modulation of transporters and enzymes in the female lower genital tract. However, no systematic information on transporter/enzyme expression is available for ectocervical and vaginal tissues of premenopausal women, the genital sites most relevant to microbicide drug delivery. The current study utilized reverse transcriptase polymerase chain reaction (RT-PCR) to examine the mRNA expression profile of 22 transporters and 19 metabolizing enzymes in premenopausal normal human ectocervix and vagina. Efflux and uptake transporters important for antiretroviral drugs, such as P-gp, BCRP, OCT2, and ENT1, were found to be moderately or highly expressed in the lower genital tract as compared to liver. Among the metabolizing enzymes examined, most CYP isoforms were not detected while a number of UGTs such as UGT1A1 were highly expressed. Moderate to high expression of select transporters and enzymes was also observed in mouse cervix and vagina. The implications of this information on microbicide research is also discussed, including microbicide pharmacokinetics, the utilization of the mouse model in microbicide screening, as well as the in vivo functional studies of cervicovaginal transporters and enzymes.

  17. Comparative Research to Surface Aeration and Blasting Aeration System Based on LCC Theory

    Science.gov (United States)

    Liai, CHEN; Hongxun, HOU; Weibiao, FEI; Eryan, ZHAO

    2017-05-01

    It is difficult to select the suitable aeration system for the designers of wastewater treatment plant (WWTP). In this paper, taking two WWTPs with surface aeration systems and blasting aeration respectively for an example, LCC theory was adapted to analysis the cost of consumption and the environmental impact, which caused by the different aeration system. Research results showed that: (1) In the 20-year life cycle, the LCC mainly depended on the cost of energy consumption whatever blasting aeration system or surface aeration, while the LCC of blasting aeration system affected by the equipment maintenance cost, maintenance cost, economic losses caused by wastewater loss and environmental load in maintenance period. (2) The LCC of blasting aeration system was lower than the surface aeration in general, on the premise of the standard discharge; (3) the blasting aeration system estimated a saving of 60,0000RMB annually in costs compared with the surface aeration.

  18. Development of measuring device for inner surfaces of embedded piping (Contract research)

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Hirokuni [Ohyo Koken Kogyo Co., Ltd., Tokyo (Japan); Hatakeyama, Mutsuo [Radioactive Waste Management and Nuclear Facility Decommissioning Technology Center, Tokyo (Japan); Tachibana, Mitsuo; Yanagihara, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The measuring device for inner surfaces of embedded piping (MISE) was developed to evaluate low-level radiological contaminations of inner surfaces of piping. The MISE consists of a cylindrically-formed double layered type detector and a piping crawling robot, which were designed and manufactured separately. In measurements of the contaminations, an outer cylindrical detector close to the surface of piping measures {beta}-rays and {gamma}-rays and an inner cylindrical detector set after a shielding plate for shield of {beta}-rays measures {gamma}-rays. The {beta}-ray counting rates are derived by subtracting {gamma}-ray counts measured by the inner detector from {gamma}- and {beta}-ray counts measured by the outer detector. The piping crawling robot transports the cylindrically-formed double layered type detector with observing inner surfaces of piping. The detection limit for the contamination of {sup 60}Co was found to be about 0.17 Bq/cm{sup 2} with measurement time of 30 seconds. It is expected that 0.2 Bq/cm{sup 2} corresponding to clearance level of {sup 60}Co (0.4 Bq/g) can be evaluated with measurement time of 2 seconds, which is equal to measurement speed of 54 m/h. (author)

  19. Boundary layer drag reduction research hypotheses derived from bio-inspired surface and recent advanced applications.

    Science.gov (United States)

    Luo, Yuehao; Yuan, Lu; Li, Jianhua; Wang, Jianshe

    2015-12-01

    Nature has supplied the inexhaustible resources for mankind, and at the same time, it has also progressively developed into the school for scientists and engineers. Through more than four billions years of rigorous and stringent evolution, different creatures in nature gradually exhibit their own special and fascinating biological functional surfaces. For example, sharkskin has the potential drag-reducing effect in turbulence, lotus leaf possesses the self-cleaning and anti-foiling function, gecko feet have the controllable super-adhesion surfaces, the flexible skin of dolphin can accelerate its swimming velocity. Great profits of applying biological functional surfaces in daily life, industry, transportation and agriculture have been achieved so far, and much attention from all over the world has been attracted and focused on this field. In this overview, the bio-inspired drag-reducing mechanism derived from sharkskin is explained and explored comprehensively from different aspects, and then the main applications in different fluid engineering are demonstrated in brief. This overview will inevitably improve the comprehension of the drag reduction mechanism of sharkskin surface and better understand the recent applications in fluid engineering.

  20. Development of measuring device for inner surfaces of embedded piping (Contract research)

    CERN Document Server

    Itoh, H; Tachibana, M; Yanagihara, S

    2003-01-01

    The measuring device for inner surfaces of embedded piping (MISE) was developed to evaluate low-level radiological contaminations of inner surfaces of piping. The MISE consists of a cylindrically-formed double layered type detector and a piping crawling robot, which were designed and manufactured separately. In measurements of the contaminations, an outer cylindrical detector close to the surface of piping measures beta-rays and gamma-rays and an inner cylindrical detector set after a shielding plate for shield of beta-rays measures gamma-rays. The beta-ray counting rates are derived by subtracting gamma-ray counts measured by the inner detector from gamma- and beta-ray counts measured by the outer detector. The piping crawling robot transports the cylindrically-formed double layered type detector with observing inner surfaces of piping. The detection limit for the contamination of sup 6 sup 0 Co was found to be about 0.17 Bq/cm sup 2 with measurement time of 30 seconds. It is expected that 0.2 Bq/cm sup 2 co...